\NUFACT1 

ANDARD  SPECIFICATION 

STRENGTHENING  AND  WATERTIGHTZNINCi 

CEMENT  MORTARS  AND  CONCRETE 

PRACTICAL  APPLICATION 

USE  IN  MORTARS 


BYE.W.LAZELL,  PH.D. 


.Engineering 

T ^ 


UNIVERSITY   OF 
DEPARTMENT   OF   CIVIL    ENGINEERING 
BERKELEY,  CALIFORNIA 


Illlllllll 


Illlllllllllll IIIIUIIMIIIIIIIIIIIMIIIIM    = 

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Hydrated  Lime  I 


Illlllllllllllllllllllll lililllllf?   = 


.11 


History,  Manufacture  and  Uses  in 

Plaster  -  Mortar  -  Concrete 


1915 


A  Manual  For 
The  Architect,  Engineer, 
Contractor  and  Builder. 


By   E.  W.  LAZELL,  Ph.  D. 

Member  American  Institute  of  Chemical  Engineers. 
Member  American  Society  Mechanical  Engineers. 
Member  American  Society  for  Testing  Materials. 


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Engineering 
Library 

Copyright  1915 

by 
E.  W.  LAZELL,  Ph.  D. 


PUBLISHED    BY 

JACKSON-REMLINGER   PTG.  CO. 
PITTSBURGH,  PA. 


CHAPTERS 

Chapters  Page 

Introduction 7 

I     Historical 9 

II     Chemistry  of  Lime 11 

III  Classification  of  Lime 21 

IV  Manufacture  of  Lime 24 

V     Slaking  Lime 34 

VI     Manufacture  of  Hydrated  Lime 41 

VII     Properties  of  Hydrated  Lime 46 

VIII     Use  of  Hydrated  Lime  in  Sand  Mortars 49 

IX     Use  of  Hydrated  Lime  in  Concrete 63 

X     Advantages  of  Hydrated  Lime  over  other  forms  of  Lime ....  79 

Appendix  I — Useful  Data 81 

Appendix  II — Standard  Specifications  for  Hydrated  Lime. . .  84 
Appendix  III — Quantities  of  Materials  for  One  Cubic  Yard 

of  Plastic  Mortar  .  87 


LIST  OF  ILLUSTRATIONS 

Page 

Pyramid  of  Cheops Frontispiece 

Lime  Cycle 17 

Pot  Kiln 25 

Field  Kiln 26 

Draw  Kiln 27 

Vertical  Steel  Kiln 28 

Vertical  Steel  Kiln,  With  Stack 29 

Vertical  Producer  Gas  Kiln 32 

Modern  Installation  of  Lime  Kilns  Equipped  to  Use  Producer  Gas  33 

Clyde  Hydrator 43 

Kritzer  Hydrator 44 

Second  National  Bank  Building,  Toledo,  Ohio 51 

Equitable  Building,  New  York  City 61 

Leader-News  Building,  Cleveland,  Ohio 64 

Dam,  White  Salmon  River,  State  of  Washington  (Under  Construc- 
tion)    65 

Dam,  White  Salmon  River,  State  of  Washington  (Completed) ....  67 

Concrete  Road,  Garret  Co.,  Maryland 68 

Armory,  York,  Pa 69 

Reservoir,  Waltham,  Mass 72 

Ambursen  Hollow  Dam,  Portland,  Ore 76 

Hotel  Oregon,  Portland,  Ore 78 


821018 


INTRODUCTION 

IN  presenting  this  book  to  the  public,  the  purpose  has 
been  to  direct  the  attention  especially  of  architects  and 

builders  to  the  comparatively  new  form  of  lime  "Hydrated 
Lime,"  which  possesses  many  advantages  over  the  older 
Lump  Lime. 

The  art  of  using  lime  is  one  of  the  very  oldest  connected 
with  the  building  trade  and  was  probably  brought  to  its 
greatest  perfection  by  the  Greeks  and  Romans.  Since  these 
ancient  times  until  very  recently  little  or  no  improvement  has 
been  introduced  in  the  preparation  of  plaster  or  stucco  made 
from  lime.  Probably  the  reason  for  this  is  the  time  and  care 
required  to  slake  the  lump  lime  used  to  prepare  the  mortar. 
With  the  use  of  hydrated  lime  the  time  required  to  slake  and 
age  the  quick  lime  is  done  away  with. 

It  has  been  my  aim  to  collect  together  in  convenient 
form  the  available  data  on  this  subject.  Use  has  been  made 
of  previous  publications  and  much  information  has  been  ob- 
tained from  the  technical  press.  Especial  mention  must  be 
made  of  the  works  of  Vitruvius,  Vicat,  Miller  and  Hodgson 
and  the  various  publications  of  the  different  Bureaus  of  the 
United  States  Government.  It  is  hoped  that  the  book  may 
prove  useful  in  calling  attention  to  the  characteristics  of 
hydrated  lime  and  describing  its  various  uses. 

1915  E.  W.  LAZELL,  Ph.  D. 


HISTORICAL 

CHAPTER  I 

r  I  "MIE  use  of  lime  as  a  binding  material  or  mortar  for  holding  together 
stone  and  brick  originated  in  the  remote  past.  It  is  probable 
some  savages,  having  used  stones  composed  of  limerock  to  con- 
fine their  fire,  noticed  that  the  stones  were  changed  by  the  action  of 
the  heat.  A  passing  shower  slaked  the  lime  to  a  paste,  thus  the  dis- 
covery was  made  that  the  paste  was  smooth  working  and  furnished  a 
better  material  than  clay  to  fill  up  the  holes  and  crevices  in  their  crude 
dwellings.  From  the  discovery  of  the  fact  that  burned  limerock  gave 
a  material  which  slaked  with  water  to  a  paste,  it  was  but  a  step  to  the 
addition  of  sand  in  order  to  produce  a  mortar. 

The  art  of  using  mortar  in  some  form  or  other  is  as  old  as  the  art 
of  building  or  as  civilization  itself.  Evidences  of  the  use  of  mortar  are 
found  not  only  in  the  older  countries  of  Europe,  Asia  and  Africa,  but 
also  in  the  ruins  of  Mexico  and  Peru.  The  remains  of  the  work  of  these 
ancient  Artisans  are  evidence  to  us  of  the  enduring  qualities  of  lime 
mortar  as  well  as  the  skill  and  knowledge  possessed  by  the  user.  Miller 
in  his  work  on  mortar  states  "Plastering  is  one  of  the  earliest  instances 
of  man's  power  of  inductive  reasoning,  for  when  men  built  they  plastered; 
at  first,  like  the  birds  and  beavers,  with  mud;  but  they  soon  found  out 
a  more  lasting  and  more  comfortable  method,  and  the  earliest  efforts  of 
civilization  were  directed  to  plastering.  The  inquiry  into  it  takes  us 
back  to  the  dawn  of  social  life  until  its  origin  becomes  mythic  and  pre- 
historic. In  that  dim,  obscure  period  we  cannot  penetrate  far  enough 
to  see  clearly,  but  the  most  distant  glimpses  we  can  obtain  into  it  shows 
us  that  man  had  very  early  attained  almost  to  perfection  in  compound- 
ing material  for  plastering.  In  fact,  so  far  as  we  yet  know,  some  of  the 
earliest  plastering  which  has  remained  to  us  excels,  in  its  scientific  com- 
position, that  which  we  use  at  the  present  day,  telling  of  ages  of  experi- 
mental attempts.  The  pyramids  of  Egypt  contained  plaster  work 
executed  at  least  4000  years  ago,  and  this,  where  wilful  violence  has  not 
disturbed  it,  still  exists  in  perfection,  outvying  in  durability  the  very 
rock  it  covers,  where  this  is  not  protected  by  its  shield  of  plaster." 

The  earliest  known  examples  of  the  employment  of  mortar  in 
masonry  are  presented  by  the  pyramids  of  Egypt.  Vicat  in  his  cele- 
brated treatise  on  Mortars  and  Concrete,  states:  "The  Egyptian 
monuments  present  without  doubt  the  most  ancient  and  remarkable 


examples  which  we  can  quote  of  the  use  of  lime  in  building.  The  mortar 
which  binds  the  blocks  of  the  pyramids,  and  more  particularly  those  of 
Cheops,  is  exactly  similar  to  our 'mortars  in  Europe.  That  which  we 
find  between  the  joints  of  the  decayed  buildings  at  Ombos,  at  Edfou, 
in  the  Island  of  Phila,  and  in  other  places,  gives  evidences  by  its  color, 
of  a  reddish  very  fine  sand  mixed  with  lime  in  the  ordinary  proportion. 
The  use  of  cements  (limes)  was  therefore  already  known  two  thousand 
years  before  our  time;  perhaps  it  would  be  easy  to  carry  that  epoch 
still  farther  back,  were  we  to  consult  the  ancient  monuments  of  India, 
and  the  Sanscrit  books,  if  they  speak  of  the  ancient  relations  of  Egypt 
with  that  country;  but  this  would  be  to  attach  too  much  importance 
to  an  inquiry,  more  curious  than  useful." 

At  a  very  early  period  the  Greeks  used  plaster  consisting  of  a  true 
lime  stucco  of  most  exquisite  composition,  thin,  fine  and  white.  The 
houses  of  the  simple  citizen  were  ornamented  with  stucco  which  for 
whiteness,  hardness  and  polish  compared  well  with  the  Parian  marble. 
Thus  at  the  time  of  Pericles  and  Plato,  the  art  of  plastering  had  made 
great  progress.  From  the  Greeks  the  Etruscans,  of  middle  Italy,  gained 
their  knowledge  and  the  Romans  in  turn  learned  the  art  of  plastering 
from  them.  Greece  became  a  Roman  province  in  145  B.  C.,  and  the 
loot  of  it  gave  a  great  impetus  to  Roman  art.  Our  knowledge  of  the 
Roman  methods  of  building  and  their  use  of  material  is  largely  derived 
from  the  writings  of  Vitruvius.  Vitruvius  was  a  military  engineer 
under  Julius  Ceasar  in  his  African  campaign  and  was  an  architect  under 
Augustus.  On  all  matters  relative  to  Greek  and  Roman  architecture, 
Vitruvius  should  be  consulted,  since  according  to  his  own  confession 
his  work  contained  all  the  knowledge  that  the  Greeks  possessed  of 
the  art  of  building.  Pliny  the  elder,  in  his  natural  history,  and 
Palladius,  have  added  nothing  to  what  Vitruvius  had  said  before  them. 
The  writings  of  Vitruvius  will  be  referred  to  later  in  other  chapters, 
since  his  monumental  work  on  architecture  remained  a  standard  refer- 
ence book  until  well  into  the  18th  Century. 

The  Arabians  and  Moors  both  became  experts  in  plastering  as  is 
evident  by  the  splendid  plaster  work  still  to  be  seen  on  the  Alhambra. 

As  early  as  the  beginning  of  the  16th  Century,  the  art  of  plastering 
had  made  considerable  progress  in  England  and  "The  Plasterers  Com- 
pany*' was  incorporated  in  1501. 

This  brief  review  of  the  art  of  plastering  as  practiced  by  the  Ancients, 
will  give  an  idea  of  the  possibilities  of  the  use  of  lime  as  well  as  proving 
its  enduring  qualities.  It  is  indeed  sad  to  state  that  the  present  status 
of  the  art  does  not  nearly  reach  the  perfection  attained  by  the  Greeks 
and  Romans,  and  it  is  with  a  wish  to  interest  the  public  in  the  various 
uses  of  lime  mortar  that  this  treatise  was  undertaken. 

10 


CHEMISTRY  OF  LIME 

CHAPTER  II 

ANY  change  which  alters  the  composition  and  structure  of  matter 
is  a  chemical  change.  A  familiar  illustration  of  this  is  the  burning 
of  coal  in  which  case  both  the  composition  and  structure  are 
changed.  It  therefore  follows  since  the  structure  and  composition  of 
lime  are  changed  by  burning  that  a  chemical  reaction  has  taken  place. 
If  the  changes  brought  about  by  burning  and  slaking  lime  are  to  be 
understood  some  knowledge  of  chemistry  is  necessary. 

From  a  chemical  standpoint,  the  changes  which  take  place  in  the 
manufacture  of  lime  from  limestone  and  the  subsequent  changes  in 
slaking  and  hardening  are  comparatively  simple  and  do  not  involve 
an  extended  knowledge  of  chemistry.  In  order  to  render  the  subject 
clear,  the  various  chemical  terms  involved  will  be  explained  and  denned. 

All  matter  is  made  up  of  one  or  more  elementary  substances,  or 
chemically  speaking,  all  matter  is  made  up  of  one  or  more  elements. 
An  element  is  a  primary  form  of  matter  which  cannot  be  reduced  to  a  simpler 
form  by  any  means  known  to  science.  There  are  some  80  of  these  elemen- 
tary forms  of  matter  known,  and  of  these  only  about  a  dozen  are  involved 
in  the  chemistry  of  lime.  These  elementary  substances  combine  with 
each  other  forming  compounds  in  a  certain  known  definite  manner.  Thus 
a  compound  is  the  product  resulting  from  the  union  of  two  or  more  dis- 
similar elements. 

Modern  science  recognizes  three  divisions  of  matter,  Mass,  Molecule 
and  Atom.  Mass  alone  is  appreciable  to  the  senses.  The  other  divisions 
being  far  too  minute  to  be  reached  by  any  power  of  observation.  Mole- 
cule is  the  term  used  to  designate  the  smallest  particle  of  matter  that  can 
exist  and  still  preserve  the  properties  of  the  substance.  It  is  formed  by  a 
union  of  atoms  which  may  be  like  or  unlike,  few  or  many ;  it  is  constant 
and  regular  in  the  disposition  of  its  parts  and  bound  together  by  strong 
forces.  The  use  of  the  term  "atom"  is  from  theoretical  rather  than 
experimental  considerations.  Experiment  has  shown  that  a  definite 
quantity  of  each  element  always  enters  into  combination,  and  theory 
assumes  that  the  smallest  quantity  entering  into  any  combination  is  an 
"atom."  An  atom  can  be  defined  as  the  smallest  part  of  an  element  that 
can  enter  into  combination  with  another  element. 

11 


Although  the  atom  in  all  cases  is  too  small  to  be  weighed  individually, 
the  relative  weight  of  each  kind  of  atom  has  been  carefully  obtained  as 
the  result  of  experiment.  The  weights  of  the  various  atoms  have  been 
determined  relatively  by  comparing  them  with  hydrogen  (the  lightest 
known  element)  which  is  taken  as  unity  or  one.  These  relative  weights 
arc  called  the  "Atomic  Weights." 

TABLE  No.   1 

Atomic  weights  of  the  common  elements 

Name  Chemical  Symbol  Atomic  Weights 

Hydrogen  H  1 

Oxygen  O  16 

Carbon  C  12 

Calcium  Ca  40 

Magnesium  Mg  24 

Aluminum  Al  27 

Iron  (ferrum)  Fe  56 

Silicon  Si  28 

Sulphur  S  32 

NOTE — The  atomic  weight  is  given  to  the  nearest  whole  number  as 
this  is  sufficiently  accurate. 

The  atomic  weight  of  an  element  means  that  the  weight  of  its  atom 
is  so  many  times  heavier  than  the  weight  of  an  atom  of  hydrogen.  For 
example,  the  weight  of  an  atom  of  oxygen  is  16  times  greater  than  that 
of  an  atom  of  hydrogen. 

For  convenience  abbreviations  are  used  for  all  elements.  These 
abbreviations  are  known  as  Chemical  Symbols.  Chemical  Symbols  serve 
not  only  as  an  abbreviation  for  the  name  of  the  element,  but  the  chemist 
employs  them  to  indicate  the  composition  of  the  compound  and  the 
number  of  atoms  of  the  element  in  the  compound.  Thus  the  symbol 
for  calcium  carbonate  is  written  CaCO3.  In  which  "Ca"  stands  for 
calcium,  "C"  for  carbon  and  "O"  for  oxygen.  The  symbol  further 
indicates  that  there  is  present  in  each  molecule  of  calcium  carbonate 
one  atom  of  "Ca,"  one  atom  of  "C"  and  three  atoms  of  "O."  If  the 
atomic  weight  of  the  elements  are  inserted  in  the  place  of  the  symbol, 
we  have  Ca  =  40,  C  =  12,  O  =  16,  O3  =  48,  total  40+12+48  =  100,  the 
molecular  weight  of  calcium  carbonate.  The  molecular  weight  of  a  com- 
pound therefore  is  the  sum  of  the  weights  of  the  atoms  making  up  the  com- 
pound. 

Knowing  the  molecular  weights  of  a  substance  arid  the  elements 
of  which  it  is  composed,  it  is  possible  to  calculate  its  percentage 

W 


composition.    As  an  illustration,  take  calcium  carbonate,  the  percentage 
of  each  element  present  is: 

Ca  40/100  =  40% 
C  12/100  =  12% 
O  48/100  =  48% 

Calcium  carbonate  can  also  be  considered  as  composed  of  calcium 
oxide  (CaO)  and  carbon  dioxide  (CO2). 

Calcium  oxide  (Ca+O)    40+16=   56 

Carbon  dioxide  (carbonic  acid  gas)         (C+O2)     12+32=   44 

100 

Therefore,  there  is  present  in  calcium  carbonate: 
56/100  =  56%  CaO  (lime) 
44/100  =  44%  CO2  (carbon  dioxide) 

The  compounds  of  the  above  elements  most  useful  to  the  student 
of  lime  are  the  oxides,  hydroxides,  hydrates  and  carbonates.  These 
various  compounds  of  the  elements  given  in  Table  No.  1  are  illustrated 
in  Table  No.  2. 

TABLE  No.  2 


Elementary 
Substance 

Union  of  Two  or  More  Elementary  Substances 

or 
Element 

or 
Compounds 

With  Oxygen 
Oxides 

With  Water 
Hydroxides 
Hydrates 

With  Carbon  Dioxide 
Carbonates 

Name 

c 

1 

i 

Name 

C/3 

3  _b 

1^ 

Name 

I 

Molecular 
Weight 

Name 

V) 

Molecular 
Weight 

Hydrogen 

TT 

i 

Water 

H2O 

18 

Oxygen 

O 

16 

Carbon 

c 

12 

/  Carbon 
\  Dioxide 

C02 

44 

Calcium 

Ca 

40 

(  Calcium 
|  Oxide 
(  Lime 

CaO 

56 

Calcium 
Hydroxide 

Ca(OH)2 

74 

Calcium 
Carbonate 

CaCO3 

100 

Magnesium 

M 

24 

C  Magn'm 
j  Oxide 
(.  Magnesia 

MgO 

40 

Magnesium 
Hydroxide 

Mg  (OH)2 

58 

Vlagnesium 
Carbonate 

MgC03 

84 

Aluminum 

Al 

27 

(  Alumn'm 
j  Oxide 
(.  Alumina 

A1203 

102 

Aluminum 
Hydroxide 

A12(OH)6 

156 

Iron(Fermm) 

Fe 

56 

f  Ferric 
I  Oxide 

Fe203 

160 

Ferric 
Hydroxide 

Fe2(OH)6 

214 

Iron 

Fe 

56 

(  Ferrous 
I  Oxide 

FeO 

72 

Ferrous 
Hydroxide 

Fe(OH)2 

90 

(  Silicon 

Silicon 

Si 

28 

\  Oxide 

SiO2 

60 

1  Silica 

Sulphur 

s 

32 

f  Sulphur 
\  Dioxide 

S02 

64 

13 


BURNING — The  chemical  change  which  takes  place  in  burning  lime 
consists  in  destroying  the  bond  between  the  calcium  oxide  and  carbon 
dioxide.  This  change  is  illustrated  by  'using  the  chemical  symbols  in 
the  form  of  an  equation  and  for  a  perfectly  pure  calcium  carbonate  the 
chemical  change  can  be  illustrated  as  follows: 

Calcium  carbonate + heat  =  calcium  oxide + carbon  dioxide 
(limestone)  (lime)  (gas) 

CaCO3  +heat  =  CaO  +CO2 

100  + heat  =  56  +44 

This  equation  shows  that  the  calcium  carbonate  has  been  broken 
up  into  two  dissimilar  substances  by  the  action  of  heat,  one  of  which  is 
a  solid  (lime)  and  the  other  a  gas  (carbon  dioxide) .  Further,  it  indicates 
that  100  parts  by  weight  of  calcium  carbonate  yield  56  parts  by  weight 
of  lime,  and  that  44  parts  by  weight  of  carbon  dioxide  are  driven  off  by 
heat. 

In  the  change  produced  by  burning,  the  gas  (carbon  dioxide)  is 
carried  out  of  the  kiln  together  with  the  products  of  combustion  of  the 
fuel.  Nothing  but  the  carbon  dioxide  is  removed,  except  any  moisture  or 
organic  matter  which  may  have  been  present  in  the  stone.  The  solids, 
lime,  magnesia  and  all  other  substances,  remain  in  the  burned  lime. 

If  the  limestone  contained  5%  of  impurities,  such  as  silica  or  clay, 
these  would  have  remained  in  the  burned  product.  In  this  case  in  100 
parts  of  the  impure  stone  there  would  be  95  parts  of  calcium  carbonate. 
These  95  parts  of  calcium  carbonate  would  yield  95/100X56  =  53.2  parts 
of  calcium  oxide,  the  total  matter  remaining  after  burning  would  be 
53.2+5  or  58.2  parts  of  impure  lime,  since  the  5  parts  of  impurities  can- 
not be  removed  by  burning. 

The  percentage  composition  of  the  burned  lime  would  be: 

53.2 

=  91.4%  calcium  oxide 

58.2 

is 

8.6%  impurities 


58.2 

The  presence  therefore  of  5%  of  silica  or  clay  in  the  original  limestone 
has  reduced  the  amount  of  lime  (calcium  oxide)  in  the  burned  product 
from  100%  to  91.4%  or  nearly  9%. 

In  a  similar  manner  the  burning  of  a  dolomitic  limestone  may  be 
illustrated  as  follows: 

14 


Dolomite  -f-  heat  =  Dolomitic  lime 

Calcium  and  magnesium  carbonate  +heat  =  calcium  and  magnesium  oxide  +carbon  dioxide 

CaCO3,  MgCO3  +heat  =   CaO,  MgO  +  2CO2 

100         84  (184)  +heat=   56       40  (96)       +  88 

The  percentage  composition  of  the  dolomitic  lime  would  be  as 
follows : 

56 
-  =  58.34%  Calcium  oxide  (CaO) 

i/O 

40 

—  =  41.66%  Magnesium  oxide  (MgO) 

yo 

One  hundred  and  eighty-four  pounds  (184  Ibs.)  of  dolomitic  lime- 
stone yield  96  Ibs.  of  dolomitic  lime  or  52.17%  (96 -=-184  =  52.17%): 
that  is  100  Ibs.  of  dolomite  yields  only  52.17  Ibs.  of  dolomitic  lime,  con- 
sisting of  the  oxides  of  calcium  and  magnesium. 

From  the  preceding  equations  it  will  be  seen  that  the  amount  of 
impurities  present  in  the  stone  increased  the  yield  of  the  burned  product, 
although  at  the  same  time  it  decreased  the  amount  of  oxides  of  calcium 
and  magnesium  present  in  the  burned  material  (5  Ibs.  of  impurities 
present  in  the  stone  decreases  the  amount  of  the  oxides  of  calcium  and 
magnesium  contained  in  the  burned  product  to  about  91%).  Further 
it  will  be  noted  that  100  Ibs.  of  dolomitic  limestone  gave  only  52.17 
Ibs.  of  burned  material,  while  100  Ibs.  of  high  calcium  limestone  gave 
56  Ibs.  of  burned  material,  thus  the  presence  of  magnesia  decreases 
the  yield  from  100  Ibs.  of  stone. 


SLAKING  OR  HYDRATING  LIME 

As  is  well  known,  when  quick-lime  is  treated  with  water,  heat  is 
generated  and  a  product  is  formed  which  has  an  entirely  different  char- 
acter than  the  original  quicklime.  This  indicates  that  a  chemical  reac- 
tion has  taken  place  which  can  be  expressed  for  the  two  groups  of  limes 
as  given  below: 

High  calcium  quicklime + water  =  high  calcium  hydrate 
CaO  +H20    =Ca(OH)2 

56  +18       =74 

In  this  reaction  56  parts  by  weight  of  high  calcium  quicklime  have 
combined  with  18  parts  by  weight  of  water  producing  74  parts  by  weight 
of  dry  hydrate.  This  dry  hydrate  contains  the  original  amount  (56 
parts)  of  quicklime,  but  this  material  is  not  present  as  quicklime  since 

15 


it  has  chemically  combined  with  the  water.  In  case  more  than  the 
exact  amount  of  water  necessary  to  form  the  chemical  hydrate  is  present, 
this  water  is  simply  mechanically  mixed  with  the  hydrate  forming  a 
lime  paste.  Calcium  oxide  is  the  only  compound  present  in  the  lime 
which  actively  combines  with  water,  in  the  ordinary  methods  of  slaking. 
For  dolomitic  quicklime  the  reaction  of  slaking  is  expressed  by 
the  following  equation: 

Dolomitic  quicklime + water  =  Dolomitic  hydrate 
CaO    MgO        +H20    =Ca(OH)2    MgO 
96  +18       =       114 

By  comparing  this  equation  with  the  one  for  high  calcium  quick- 
lime it  will  be  noticed  that  less  water  has  been  combined  in  the  slaking. 
The  reason  for  this  is  that  the  magnesium  oxide  contained  in  dolomite 
is  rendered  inert  at  the  temperature  of  burning  and  does  not  combine 
chemically  with  the  water,  but  remains  present  in  the  hydrate  as  mag- 
nesium oxide.  Thus  dolomitic  hydrate  consists  of  a  mixture  of  calcium 
hydrate  and  magnesium  oxide.  It  is  for  this  reason  that  it  requires  a 
greater  weight  of  dolomitic  quicklime  to  produce  the  same  weight  of 
hydrate.  The  amount  of  caustic  oxides  present  in  the  dolomitic  hydrate 
is  greater  than  in  the  high  calcium  hydrate.  The  above  equation  was 
calculated  for  a  pure  dolomite  containing  58.5%  lime  and  41.5% 
magnesia. 

HARDENING — The  hardening  of  lime  mortar  is  due  to  the  lime  and 
magnesia  present  in  the  mortar  combining  with  the  carbon  dioxide  of 
the  atmosphere.    The  chemical  change  that  takes  place  can  be  illustrated 
by  the  following  equation: 
Calcium  hydrate  + Carbon  dioxide  =  Calcium  carbonate       + water 

Ca(OH)2        +  CO2  =CaCO3  +H2O 

74  +44  =100  +18 

Magnesium  oxide + Carbon  dioxide  =  Magnesium  carbonate 

MgO  +C02  =Mg  CO3 

40  +44  =84 

From  the  foregoing  explanation,  it  will  be  seen  that  lime  passes 
through  three  distinct  chemical  phases  in  its  change  from  the  stone  to 
the  hardened  mortar.  These  three  phases  form  a  cycle,  and  in  the  end 
lime  has  returned  to  its  original  form.  These  three  changes  have  been 
illustrated  and  are  given  below: 

1st— Burning  CaCO3     +heat  =  CaO  +  CO2 

2nd— Slaking  CaO         +H2O  =  Ca(OH)2 

3rd— Recarbonating  (hardening)        Ca(OH)2+CO2  =CaCO3+H2() 

These  changes  have  been  graphically  illustrated  by  the  author  as 
the  "Lime  Cycle."  Page  No.  17. 

16 


LIME|CTCLE 

Showing  the  Sequence  of  the  Changes  Produced  by  Burning,   Slaking  and 

Hardening,  and  that  these  Changes  Form  a  Complete  Cycle;  the 

Lime  Returning  to  its  Original  Carbonate  Form. 

Copyrighted,  E.  W.  Lazell,  1911 


17 


A  familiarity  with  the  chemical  terms  and  the  changes  which  take 
place  in  the  manufacture  and  use  of  lime  has  a  further  advantage  both 
to  the  manufacturer  and  user  in  that  it  renders  easy  the  interpretation 
of  the  results  of  a  chemical  analysis  of  limestone  and  lime.  This  can  best 
be  explained  by  starting  with  the  analysis  of  a  natural  sample  of  lime- 
stone and  dolomite  and  following  the  two  cycle  change  produced  by 
burning  and  slaking. 

High  Calcium  Dolomitic 

Chemical  Terms                           Symbol       Limestone  Limestone 

Per  Cent.  Per  Cent. 

Silica                                                  SiO2                 1.00  .93 

Alumina                                            A12O3  )                 Qft  oQ 
Ferric  oxide                                      Fe2O3  J 

Lime                                                    CaO               54.24  32.73 

Magnesia                                           MgO                  .80  19.37 

Carbon  dioxide  )   ,T  T    ...    v  CO2  )  ,,0  ft«  /t«  KQ 

1  .r   .  >   (Loss  on  Ignition)  TT  Q  f  43  .  Uo  4o  .  58 

All  the  above  ingredients  may  be  classed  under  three  heads;  im- 
purities: silica,  alumina  and  iron  oxide;  material  removed  by  burning: 
carbon  dioxide  and  water;  and  the  lime  ingredient:  lime  and  magnesia, 
the  only  two  materials  which  confer  valuable  properties  on  the  burned 
product. 

It  is  possible  from  the  above  analysis  to  calculate  the  composition 
of  the  lime  which  would  be  produced  by  burning  either  of  the  above 
stones.  The  amount  of  material  indicated  by  loss  on  ignition  is  that 
portion  which  is  driven  off,  all  the  other  ingredients  remaining  in  the 
burned  product.  It  follows  therefore,  that  from  100  parts  of  the  above 
high  calcium  stone  there  would  remain  after  burning  only  56.94  parts 
of  high  calcium  lime  (100—43.06  [loss  on  ignition]  =56.94).  The  quan- 
tities of  the  various  ingredients  other  than  those  included  in  loss  on 
ignition  are  present  in  the  lime;  therefore,  the  percentage  composition 
of  the  burned  lime  is  calculated  as  follows: 


10006 


on 


Al203+Fe208  ^T94=   l  '58% 

CaO  !t4/  =  9. 


MgO  ^  ~=   1.40% 

18 


The  composition  of  the  lime  produced  from  the  dolomitic  lime- 
stone is  derived  in  a  similar  manner: 


AlA+FesO,  —     =      .73% 

Ca°     •"  =6 


These  illustrations  show  that  in  order  to  derive  the  composition  of 
any  lime  produced  from  a  stone  of  known  analysis  it  is  only  necessary 
to  divide  the  percentage  amount  of  the  ingredient  by  the  difference 
obtained  by  subtracting  the  percentage  given  for  the  loss  on  ignition 
from  100. 

The  calculation  of  the  composition  of  the  hydrates  derived  from  the 
above  limes  by  slaking  is  not  quite  so  simple,  still  nothing  is  involved 
more  complicated  than  the  rule  of  three.  As  has  been  stated  before, 
lime  is  the  only  compound  present  which  combines  with  water,  and  this 
combination  takes  place  according  to  the  equation 

CaO+H2O  =  Ca  (OH)2 
56     +18     =  74 

or  each  56  parts  by  weight  of  lime  give  74  parts  of  hydrate;  then  the 
95.26  parts  of  lime  would  give: 

56:74  as  95.26:X     X  =  125.88 

100  parts  of  the  high  calcium  lime  would  yield  on  hydrating  as  follows: 
SiO2  No  change  1  .  75  parts 

Al2O3-hFe2O3          No  change  1  .  58 

CaO  Change  to  hydrate  125  .  88 

MgO  No  change  1.40 

Total  130.61 

The  percentage  composition  of  this  hydrate  would  be  as  follows: 


Al203+Fe203  =   1.21% 

Ca(OH)2 


19 


In  the  same  manner,  the  hydrate  produced  from  the  dolomitic 
lime  can  be  calculated.     In  this  lime  there  is  61.27%  of  lime  and  this 
amount  would  yield  on  hydration  as  follows: 
56:74  =  61.  27:X     X  =  80.96 

SiO2  No  change  1  .  74  parts 

Al2O3+Fe2O3          No  change  .73 

Ca(OH)2  Changed  to  hydrate  80  .  96 

MgO  No  change  36.  26 

Total  '" 


The  percentage  composition  of  this  hydrate  would  be  as  follows: 


A,203+Fe203  -      .61 


In  the  foregoing  the  attempt  has  been  made  to  explain  clearly  and 
simply  the  chemical  changes  which  take  place  in  the  manufacture  and 
use  of  lime  —  some  knowledge  of  this  subject  is  necessary  for  the  manu- 
facturer if  the  material  is  to  be  prepared  in  a  proper  manner.  The  user 
of  lime  also  should  understand  the  action  of  burned  lime  if  the  material 
is  to  be  handled  to  the  best  advantage. 


20 


CLASSIFICATION  OF  LIME 

CHAPTER  III 

ORIGIN  Limestone  is  the  raw  material  from  which  lime  is  manufactured. 
In  general,  limestones  have  been  formed  by  accumulation  of 
remains  of  sea  organisms,  such  as  the  foraminifera,  corals  and  mollusks 
at  the  bottom  of  the  sea.  These  limestones  sometime  show  the  fossil 
remains  from  which  they  were  formed  while  in  other  instances  all  trace 
of  their  organic  origin  has  been  destroyed. 

DEFINITION  OF    The  term  "limestone"  as  used  in  the  lime  industry 
LIMESTONE  may  be  defined  as  a  general  term    referring  to  that  class 

of  rocks  containing  80%  or  over  of  the  carbonates  of 
calcium  and  magnesium,  which,  when  calcined,  give  products  which  slake 
upon  the  addition  of  water.  Limestones  are  generally  differentiated 
geologically,  based  upon  their  different  origin,  texture  and  composition. 
Depending  upon  their  physical  appearance,  the  most  important  varieties 
are  as  follows: 

CLASSES  OF     Marble — Limestone   having   a   coarse   or   fine   crystalline 
LIMESTONE      structure  which  has  been  produced  by  heat  and  pressure. 
Chalk — A  soft  friable  limestone  composed  of  finely  divided 
shells  consisting  principally  of  those  of  the  foraminifera. 
Oolitic  Limestone — (Oolite) — A  limestone  made  up   of  small  rounded 
grains  so  named  because  of  its  supposed  resemblance  to  fish-roe. 
Marl — A  soft  friable  material  made  up  of  grains  of  carbonate  of  lime 
generally  found  in  lake  basins. 

COMPOSITION  OF    Depending   upon  their   composition,   limestones   are 
LIMESTONE  generally  distinguished  as  follows: 

Argillaceous    or    clayey    limestone,    containing    con- 
siderable clay. 

Arenaceous  or  silicious  limestone,  containing  considerable  silica  or  sand. 
Conglomerate  Limestone,  containing  large  pebbles  of  lime-rock. 
Dolomite,   a  double  carbonate  of  calcium  and   magnesium  containing 
when  pure  54.35%  of  calcium  carbonate  and  45.65%  of  magnesium 
carbonate. 

Magnesian  Limestone,  containing  between  10  and  30%  of   magnesium 
carbonate. 

High  Calcium  Limestone,  a  limestone  containing  not  more  than  10%  of 
magnesium  carbonate. 

NOTE — The  preceding  defiinitions  are  taken  largely  from  the  paper  presented  by 
Irving  Warner  and  the  author  before  the  National  Lime  Manufacturers'  Association 
in  1910. 

21 


DEFINITION     Lime  may  be  defined  as  the  product  resulting  from  the 
OF  LIME          calcination  of  a  limestone  consisting  essentially  of  the  car- 
bonates of  calcium  and  magnesium,  which  slakes  upon  the 
addition  of  water. 

Since  all  limes  are  made  from  limestone,  it  follows  that  a  classi- 
fication of  lime  might  be  introduced  which  would  indicate  the  origin  of 
the  lime  or  the  kind  of  stone  from  which  it  was  made.  Following  this 
system,  the  term  "Marble  lime'*  would  indicate  that  the  lime  was  pro- 
duced from  marble;  " Argillaceous  lime"  one  produced  from  a  argill- 
aceous limestone  and  the  "Silicious  lime"  one  produced  from  a  silicious 
limestone,  etc.  Such  a  classification,  however,  would  have  little  practical 
value  for  the  building  trades.  A  more  rational  classification  is  therefore 
based  upon  the  chemical  composition  of  the  stone  and  the  form  in  which 
the  lime  is  brought  into  the  market. 

TYPES  OF  Classification  of  lime  based  upon  the  chemical  composition: 
LIME  (a)  High  Calcium  Lime — Containing  at  least  90%  of  cal- 

cium oxide. 

(b)  Calcium  Lime — Containing  from  85%  to  90%  of  calcium  oxide. 

(c)  Magnesian  Lime — Containing  from  85%  to  90%  of  calcium  and 
magnesium  oxides,  10%  to  25%  being  magnesium  oxide. 

(d)  High  Magnesium  Lime — Containing  not  less  than  85%  of  calcium 
and  magnesium  oxide,  not  less  than  25%  being  magnesium  oxide. 

(e)  Hydraulic  Lime — Which  contains  so  large  a  percentage  of  lime  silicate, 
aluminate  or  ferrate  as  to  give  the  material  the  property  of  hardening 
under  water,  but  which  at  the  same  time  contains  so  much  free  lime  that 
the  burned  mass  will  slake  upon  the  addition  of  water. 

BUILDING  TRADES  Classification  of  lime  and  lime  products  based 
CLASSIFICATION  upon  the  form  in  which  they  are  supplied  the 
OF  LIME  trade: 

(a)  Run  of  Kiln  Lime — The  product  as  it  comes 
from  the  kiln,  without  any  sorting  or  further  preparation. 

(b)  Selected  Lump  Lime — A  well  burned  lime  which  has  been  freed  from 
core,  ashes  and  cinder  by  sorting. 

(c)  Ground  or  Pulverized  Lime — Lime  which  has  been  reduced  in  size  to 
pass  a  J^  inch  screen. 

(d)  Hydrated  Lime — A  dry  flocculent  powder  resulting  from  the  treat- 
ment of  quicklime  with  sufficient  water  to  satisfy  chemically  all  the 
calcium  oxide  present. 

The  various  kinds  of  lime  mentioned  under  the  chemical  classifica- 
tion may  be  brought  into  the  market  in  any  of  the  above  four  forms. 
For  example,  hydrated  lime  may  be  prepared  from  a  high  calcium, 
calcium,  magnesian  or  high  magnesian  lime. 

22 


CLASSIFICATION  OF          The  terms  fat  and  lean  are  often  applied  to 
LIMES  AS  FAT,  lime  and  refer  only  to  the  working  qualities  of 

LEAN  OR  HYDRAULIC     the  paste  and  not  to  the  chemical  composition. 

A  fat  or  rich  lime  is  a  term  employed  by  the 

users  of  lime,  to  express  smooth  working  qualities  and  great  sand  carry- 
ing capacity.    A  lean  or  poor  lime  is  the  opposite  of  a  fat  lime. 

Lieut.  W.  H.  Wright  in  his  book  on  Mortars  published  in  1845 
classified  limes  as  follows:  "Lime  which  is  used  for  building  purposes 
is  rarely  pure  lime,  but  besides  water  and  carbonic  acid  imbibed  from 
the  atmosphere  contains  usually  some  foreign  substances.  These  sub- 
stances modify  the  properties  of  pure  lime,  and,  when  combined  with 
it  in  certain  proportions,  entirely  change  its  nature.  It  will  therefore 
be  convenient  to  arrange  the  limes  employed  in  construction  into  four 
different  classes,  1st,  the  fat  limes;  2nd,  the  poor  or  meager  limes;  3rd> 
the  hydraulic  limes  and  4th,  the  hydraulic  cements. 

"The  fat  limes  are  more  than  doubled  in  volume  during  the  process 
of  slaking,  which  is  always  attended  with  much  heat.  If  converted 
into  paste  and  immersed  in  water,  they  wTill  remain  of  a  soft  consistency 
forever  *  *  *  .  Builders  call  them  fat  limes,  because  the  paste, 
which  they  form  with  water,  is  soft  and  unctuous  to  the  touch. 

"The  poor  or  meager  limes  include  all  those  which,  in  slaking,  do 
not  undergo  an  increase  of  volume  equal  to  twice  their  original  bulk, 

but  exhibit,  when  immersed,  the  same  qualities  as  the  rich  limes,     * 

*     * 

"The  hydraulic  limes  possess  the  property  of  setting  under  water, 
in  periods  of  time  varying  from  one  to  forty  days  after  immersion,  and 
continue  to  harden  more  or  less  rapidly,  according  to  the  hydraulic 
energy  which  they  respectively  possess.  They  all  slake,  but  with  diffi- 
culty; the  stronger  kinds  exhibiting  few  or  none  of  the  appearances 
usually  seen  in  fat  lime  during  the  slaking  process,  little  or  no  vapor 
being  formed,  and  scarcely  any  heat  disengaged;  and  they  undergo  an 
increase  of  volume,  in  the  inverse  ratio  of  their  hydraulic  energy. 

"The  hydraulic  cements  differ  from  the  limes,  in  not  slaking  at  all 
after  calcination,  unless  they  are  previously  pulverized;  and  they  then 
form  a  paste  with  water,  without  any  perceptible  disengagement  of 
heat,  or  augmentation  of  volume.  They  contain  a  large  amount  of  the 
hydraulic  base  or  principle,  and  set  under  water  in  a  much  shorter  time 
than  the  limes  require  to  set  in  air." 

The  classification  of  lime  based  upon  the  chemical  composition  and 
the  form  in  which  the  material  is  brought  into  the  market  is  the  most 
concise  and  clear,  and  it  is  recommended  that  this  classification  be  used. 

23 


MANUFACTURE  OF  LIME 


CHAPTER  IV 

LIME  is  produced  by  expelling  the  carbon  dioxide  contained  in 
limestone  by  means  of  heat.  To  accomplish  this,  it  is  necessary 
to  heat  the  stone  to  the  temperature  of  decomposition  and 
further  to  supply  sufficient  heat  to  liberate  the  gas  from  the  ston<VJMr4«~ 
scientific  terms,  to  break  the  chemical  bond  between  the  calcium  and 
magnesium  oxides  and  the  carbon  dioxide.  It  is  not  sufficient  simply  to 
heat  the  stone  to  the  point  of  decomposition,  but  it  is  necessary  to  hold 
the  stone  at  this  temperature  and  to  supply  more  heat  in  order  to  accom- 
plish the  disruption  of  the  bond.  This  disruption  does  not  take  place 
at  once,  but  requires  time;  hence,  the  stone  must  be  retained  in  the 
burning  zone  long  enough  for  the  heat  to  accomplish  its  purpose. 

Since  it  is  necessary  only  to  supply  sufficient  heat  to  the  limestone 
to  obtain  lime,  the  earliest  methods  of  burning  were  very  simple  and 
required  but  little  skill.  Perhaps  the  earliest  method  of  burning  was  a 
heap  of  stones  on  the  ground  with  logs  used  as  fuel. 

TYPE  OF      These  can  be  divided  into  two  general  classes  as  follows: 
KILNS  1st — Intermittent  Kilns. 

2nd — Continuous  Kilns. 

POT  KILN  1st — Intermittent  kilns,  usually  called  "pot  kilns,"  are 
those  in  which  each  burning  of  a  charge  constitutes  a 
separate  operation.  The  kiln  is  charged,  burned,  cooled,  and  then 
drawn.  After  completing  the  cycle,  the  kiln  is  recharged  for  another 
burning.  Such  a  kiln  often  consists  of  a  crude  shaft  excavated  in  the  side 
of  a  hill;  the  interior  of  the  shaft  being  lined  with  larger  stones  of  the 
same  material  as  those  to  be  burned.  At  the  bottom  of  the  shaft,  there 
is  a  horizontal  passage  to  the  outside.  At  the  place  where  the  horizontal 
passage  meets  the  vertical  shaft,  an  arch  of  limestone  is  made,  and  on 
top  of  this,  more  limestone  is  placed  until  the  shaft  is  completely  filled. 
A  fire  is  then  built  under  the  arch,  and  the  burning  is  continued  until 
the  stone  is  thoroughly  calcined.  Page  No.  25. 

24 


POT  KILN 
An  Early  Form  of  Lime  Kiln 


FIELD  KILN  At  a  somewhat  later  date,  kilns  were  built  in  the  open 
having  vertical  walls  of  masonry  of  a  circular  or  square 
section  but  in  other  ways  resembled  the  shaft  in  the  side  of  the  hill.  These 
early  types  of  shaft  kilns  are  still  to  be  found  scattered  throughout  the 
country.  A  description  of  such  a  kiln  given  by  Chas.  T.  Jackson,  in  the 
Third  Annual  Report  on  the  Geology  of  Maine,  published  in  1839,  states 
that  this  type  of  kiln  was  usually  "built  of  refractory  rock,  lined  with 
clay  and  laid  outside  with  mortar  15  ft.  wide — 15  ft.  high — 5  ft.  back 
Arches  middle,  5  ft.  high — side  arches,  3 j/2  ft.  high.  This  kiln  is  the  form 
commonly  used  at  Thomaston,  and  the  lime  is  burned  by  means  of  wood 
fuel,  30  cords  of  wood  being  required  to  burn  the  charge  of  rock.  The 
operations  are  divided  into  four  turns,  and  for  three  or  four  days  and 
nights  the  fire  is  kept  unremittently  in  action."  Page  No.  26. 

25 


FIELD  KILN 
Described  by  Jackson  in  1839 

Such  a  kiln  would  produce  about  300  casks,  or  45  tons  of  lime  at 
a  burning.  Jackson  further  states  that  similar  kilns  were  constructed 
of  a  circular  form. 

This  type  of  kiln  commonly  called  a  Pot  Kiln  can  never  be  economical 
since  there  is  an  enormous  loss  of  heat  at  each  burning  owing  to  the  quan- 
tity of  fuel  required  to  raise  the  contents  of  the  kiln  and  the  surrounding 
thick  stone  walls  to  the  necessary  temperature  each  time  the  kiln  is 
charged.  Further,  the  stone  nearest  the  arch  is  liable  to  become  over- 
burned  before  the  top  portion  of  the  charge  is  calcined. 

CONTINUOUS     This  class  can  be  subdivided  as  follows: 
KILNS  (a)  Vertical  kilns,  mixed  feed. 

(b)  Vertical  kilns,  separate  feed. 

(c)  Ring,  or  chamber,  kilns. 

(d)  Rotary  kilns. 

DRAW  KILN  (a)  Vertical  Kiln,  Mixed  Feed — This  type  of  kiln,  gener- 
ally called  a  draw  kiln,  is  similar  to  the  pot  kiln;  the  lime- 
stone and  fuel  are  charged  at  the  top  in  alternate  layers,  and  the  burning 
proceeds  from  a  point  near  the  top,  the  lime  being  withdrawn  at  the 
bottom.  The  advantage  of  this  type  of  kiln  is  that  it  is  cheap  to  con- 
struct, and  is  economical  in  fuel.  Its  disadvantage  is  the  discoloration 
and  contamination  of  the  burned  lime  by  the  ashes  from  the  fuel;  also 
the  ashes  combine  with  the  lime,  producing  lumps  which  prevent  thor- 
ough and  satisfactory  slaking.  An  early  kiln  of  this  type  is  illustrated 
herewith;  this  kiln  was  one  in  use  at  Thomaston,  Maine,  in  1838,  an- 
thracite coal  screenings  being  used  as  fuel.  Page  No.  27. 

26 


DRAW  KILN 
Described  by  Jackson  in  1839 

«7 


VERTICAL  STEEL  KILN 
A  Modern  Steel  Encased  Flame  Kiln. 


VERTICAL  STEEL  KILN  WITH  STACK 
A  Modern  Steel  Encased  Flame  Kiln  with  Stack  to  Increase  the  Draught 

29 


The  Aalborg  or  Schofer  kiln,  neither  of  which  has  been  much  used 
in  this  country,  illustrates  the  best  development  of  this  class  of  kiln.  The 
stone  is  charged  in  at  the  top,  while  the  fuel  is  fed  into  chutes,  which 
join  the  main  shaft  of  the  kiln  some  distance  below  the  top.  Such  kilns 
are  very  economical  in  fuel,  but  the  lime  is  contaminated  with  the  ashes. 

VERTICAL  (b)  Vertical  Kiln  with  Separate  Feed — This  is  the  most 

STEEL  KILN  common  type  of  kiln  at  present  used  in  this  country.  It 
consists  of  a  vertical  shaft  built  of  masonry  and  lined 
with  fire  brick,  having  a  round  section.  It  is  equipped  with  two  or  more 
fire  boxes  like  Dutch  ovens  for  burning  the  fuel  which  are  built  into  the 
side  of  the  kiln  near  the  bottom  so  that  the  fuel  does  not  come  in  contact 
with  the  lime.  Its  advantages  are  that  any  kind  of  fuel  can  be  used  in- 
cluding coal,  wood,  gas  or  oil,  and  the  lime  produced  is  clean  because  it 
does  not  come  in  contact  with  the  burning  fuel.  Other  things  being  equal, 
the  fuel  economy  would  not  be  so  great  as  in  class  (a)  above.  Pages 
No.  28  and  29. 

RING  KILN  (c)  Ring  or  Chamber  Kiln — This  kiln  is  generally  known  as 
the  Hoffman  Kiln,  and  it  has  been  extensively  used  for 
burning  brick,  cement  and  lime  in  Europe.  It  has  been  but  little  used  in 
this  country  for  burning  lime,  although  there  are  now  old  kilns  of  this 
type  at  Riverton,  Va.  and  Kelley  Island,  Ohio.  It  is  very  economical  in 
fuel,  producing  a  good  grade  of  lime,  but  the  labor  cost  of  operating  is 
excessive. 

ROTARY  KILN  (d)  Rotary  Kiln — This  kiln  is  the  same  as  that  commonly 
employed  for  burning  Portland  cement,  except  that 
gaseous  fuel  is  used.  The  kiln  is  very  economical  both  as  to  fuel  consump- 
tion, and  the  cost  of  labor  to  operate.  It  has,  however,  the  disadvantage 
that  limestone  fed  to  it  must  be  crushed  rather  finely,  and  hence  the 
burned  product  is  also  fine. 

FUEL  The  use  of  kilns  with  separate  fire  boxes  was  largely  brought 
about  by  the  high  cost  of  wood  and  the  necessity  of  employing  a 
cheaper  fuel,  such  as  coal.  As  long  as  wood  was  plentiful  and  cheap,  it 
was  the  fuel  most  used  for  burning  lime,  and  the  simpler  type  of  kiln 
was  practical.  With  the  increasing  scarcity  of  wood,  most  lime  plants 
have  been  forced  to  adopt  the  use  of  coal,  and  the  use  of  coal  has  in  turn 
necessitated  the  adoption  of  a  different  and  more  complicated  type  of 
kiln.  If  an  old  lime  burner  is  asked  "what  is  the  best  fuel  for  the  burn- 
ing of  lime,"  his  answer  will  be  "wood,"  since  wood  produces  a  long, 
mild  flame.  Unless  the  combustion  is  carefully  controlled  when  coal 
alone  is  used,  there  is  undoubtedly  too  short  and  intense  a  flame  to  pro- 
duce the  best  quality  of  lime. 

SO 


COAL  Methods  of  controlling  the  combustion  have  been  devised  so  that 
there  is  obtained  from  coal  the  desired  long,  mild  flame,  which 
produces  a  good  grade  of  lime.  The  most  common  of  these  methods  is 
to  introduce  steam  below  the  grates  of  the  fire  boxes.  Another  device  is 
that  known  as  the  Eldred  process.  By  this  process  a  portion  of  the  gas  is 
removed  from  the  kiln  near  the  top  by  means  of  a  fan,  and  this  gas  is 
then  mixed  with  air  and  introduced  beneath  the  grates  of  the  furnace. 
This  process  accomplishes  a  dilution  of  the  air  by  mixing  it  with  the  spent 
gas  from  the  top  of  the  kiln,  and  a  good,  long  flame  of  low  intensity  is 
produced.  This  flame  is  not  apt  to  overheat  the  lime  nor  cause  over- 
burning. 

PRODUCER     The  most  recent  advance  in  connection  with  the  use  of  coal 
GAS  is  its  gasification  in  producers,  and  the  use  of  this  gas  to 

burn  the  lime.  Producer  gas  gives  a  flame  of  low  intensity 
and  great  volume  which  resembles  closely  the  flame  of  burning  wood. 
The  producer  gas  method  of  burning  requires  more  careful  regulation  and 
more  skillful  management  than  the  other  methods.  A  number  of  pro- 
ducer gas  installations  have  proved  failures  because  of  the  lack  of  knowl- 
edge as  to  how  they  should  be  installed  and  lack  of  scientific  manage- 
ment. Pages  No.  32  and  33. 

It  will  thus  be  seen  that  from  the  simple  kilns  used  by  our  fore- 
fathers in  which  wood  was  used  as  a  fuel,  we  have  advanced  to  a  more 
complex  type  of  kiln  which  resembles  somewhat  an  iron  blast  furnace, 
and  in  which  producer  gas  is  used  as  fuel.  With  each  step  in  the  advance, 
the  amount  of  capital  required  to  construct  the  kiln  has  greatly  in- 
creased. 


VERTICAL  PRODUCER  GAS  KILN 
A  Modern  Producer  Gas  Fired  Lime  Kiln 


SLAKING   LIME 

CHAPTER  V 

CHEMICAL  CHANGE     The  term  "slaking"  refers  to  the  change  produced 

DURING  SLAKING         when  lime  is  treated  with  water.    As  is  well  known, 

PROCESS  a  violent  action  occurs  when  water  is  added  to 

lime:  the  lumps  break  up,  heat  is  generated,  and 

a  product  is  formed  which  has  an  entirely  different  character  than  the 
original  quick  lime.  This  phenomenon  indicates  that  a  chemical  reaction 
has  taken  place.  In  this  chemical  change  the  calcium  oxide  (lime)  has 
united  with  water  forming  a  new  compound,  calcium  hydroxide 
(slaked  lime).  The  chemistry  of  this  change  has  been  fully  explained 
in  the  chapter  devoted  to  the  "Chemistry  of  Lime." 

QUICK  OR  SLOW  In  order  to  render  lime  as  it  comes  from  the  kiln  suit- 
SLAKING  LIMES  able  for  use  in  mortar  it  is  necessary  to  slake  it.  This 
is  generally  accomplished  by  adding  sufficient  water  to 
the  lime  to  produce  a  thick  paste.  The  various  kinds  of  lime  mentioned 
under  the  chemical  classification  of  lime  act  in  very  different  manners 
when  treated  with  water.  The  high  calcium  limes  are  quick  slaking  and 
give  off  the  greater  amount  of  heat  because  these  limes  consist  principally 
of  calcium  oxide,  this  being  the  material  which,  by  combining  with  water, 
generates  the  heat.  As  the  amount  of  impurities  (silica,  alumina  and 
iron  oxide),  increases  the  lime  contains  less  calcium  oxide  and  is  therefore 
slower  slaking.  Such  slow  slaking  limes  are  generally  termed  "lean" 
limes. 

The  dolomitic  quick  limes  are  slower  slaking  and  generate  less  heat 
because  they  contain  less  calcium  oxide;  a  part  of  the  calcium  oxide 
being  replaced  by  magnesium  oxide  which  does  not  combine  with  water 
under  the  ordinary  conditions  of  slaking.  In  case  the  dolomitic  limes 
contain  impurities,  such  as  silica,  alumina  and  iron  oxide,  they  are 
rendered  slower  slaking  for  the  same  reason  as  given  for  the  high  cal- 
cium lime. 

METHOD  OF  The  ordinary  method  of  slaking  quick  lime  is  to  add  suf- 
SLAKING  ficient  water  to  produce  a  thick  paste  after  the  reaction  of 

slaking  is  completed.  In  this  method  of  slaking  sufficient 
water  should  be  used  in  order  that  it  may  come  in  contact  with  all  parts 
of  the  lime.  If  insufficient  water  is  used  some  parts  of  the  mass  of  lime 
become  dry  and  are  " burned"  in  slaking.  "Burned"  lime  works 

34 


tough  and  non-plastic  in  the  mortar.  If  an  excess  of  water  is  used,  the 
slaking  proceeds  slowly  and  the  resulting  paste  is  thin  and  watery. 
Such  lime  paste  is  spoken  of  as  "drowned." 

4 

Since  various  kinds  of  lime  differ  greatly  in  their  behavior  in  slak- 
ing, some  requiring  more  water  and  some  a  longer  time  to  become  re- 
duced to  a  proper  paste,  it  is  necessary  to  exercise  great  care  in  slaking. 
A  quick  slaking  lime  will  require  a  large  amount  of  water  and  this  must 
be  added  quickly,  also  the  lime  must  be  turned  over  rapidly  so  that  the 
water  has  access  to  all  parts  and  no  "burning"  takes  place  during  slak- 
ing. On  the  contrary,  the  slower  slaking  limes,  such  as  the  dolomites, 
require  less  water,  and  care  is  necessary  to  see  that  these  limes  are  not 
"drowned."  In  a  treatise  of  this  kind,  it  is  impossible  to  give  detailed 
instructions  as  to  the  best  method  of  slaking  the  individual  limes  since 
each  lime  possesses  its  own  characteristics,  particularly  as  to  its  behavior 
in  slaking.  Too  often  the  slaking  is  left  to  inefficient  and  ignorant 
labor  with  the  result  that  the  mass  of  lime  is  not  thoroughly  slaked, 
being  either  "burned"  or  "drowned." 


QUANTITY  OF  WATER 
REQUIRED  FOR  SLAKING 


Some  recent  tests  made  by  Cloyd  M.  Chap- 
man* illustrate  very  clearly  the  variation  in 


the  amount  of  water  required  to  slake  lime  to 

a  paste.    In  making  this  test  great  care  was  exercised  to  bring  the  paste 
to  a  standard  uniform  consistency. 

TABLE  No.  3— RESULTS  OF  LIME  TESTS 
HIGH   CALCIUM  LIME 


Sample  No. 
Source 

117 
York 
Pa. 

114 
Farnum 
Mass. 

116 
Farnum 
Mass. 

118 
Rock- 
land 
Me. 

120 
West 
Stock- 
bridge 
Mass. 

113 
York 
Pa. 

119 
Adams 
Mass. 

115 

West 
Stock- 
bridge 

Mass. 

Marked 

Lump 
Lime 

Lump 
Lime 

Lump 
Lime 

Lump 
Lime 

Lump 
Lime 

Lump 
Lime 

Granu- 
lar 
Lime 

Lump 
Lime 

Av. 

Analysis  CaO 
MgO 
Si02 
R2O3 
Gals,    water   per 
bbl.  to  make  putty 
Lbs.  lime  in  1  cu. 
ft.  putty 
Weight  1  cu.  ft. 
putty  in  Ibs. 

99.04 
0.65 
0.10 
0.12 

29.4 
43.1 
95.2 

98.91 

98.91 

96.81 
1.27 
0.42 
0.88 

30.5 
44.6 
100.1 

95.23 
0.71 
3.46 
0.60 

32.4 
41.2 
96.7 

95.00 

94.87 
0.84 
2.05 
1.86 

32.9 

38.6 
91.5 

84.31 
5.84 
3.54 
2.00 

28.3 
45.2 
97.8 

95.38 
1.16 

1.38 
0.77 

30.9 
41.4 
94.4 

0.73 
0.36 

32.2 

38.7 
93.0 

0.73 
0.36 

32.7 
38.0 
89.3 

0.36 
29.1 
41.8 
92.2 

*Data  on  Lime  Putty  and  Cream  of  Lime  by  Cloyd  M. 
Concrete  Institute,  November  and  December,  1914. 


Chapman,  Journal  of  American 


35 


TABLE  No.  3— RESULTS  OF  LIME  TESTS,  Cont'd 
DOLOMITIC  LIME 


Sample  No. 
Source 

121 
Dover 
Plains 
N.  Y. 

124 

Knicker- 
bocker 
Pa. 

Marked 

Dutchess 
County  Lime 

Lump  Lime 

Average 

Analysis    CaO 
MgO 
Si02 
R203 
Gals,  water  per  bbl.  to  make  putty 
Lbs.  lime  in  cu.  ft.  putty 
Weight  1  cu.  ft.  putty  in  Ibs. 

56.46 
38.54 
1.58 
1.60 
25.3 
50.6 
102.4 

56.99 
40.11 
2.11 
0.79 
22.8 
56.5 
109.0 

56.72 
39.32 
1.85 
1.14 
24.0 
53.5 
105.7 

An  inspection  of  Table  No.  3  brings  out  the  following  features: 

(1)  The  amount  of  water  required  to  make  putty  by  the  dolomitic 
limes  tested  is  about  20  per  cent  less  than  for  the  high  calcium  limes. 

(2)  The  amount  of  water  required  to  slake  and  reduce  to  a  putty 
one  barrel  of  high  calcium  lime  is  a  variable  quantity  and  for  the  samples 
tested  ranges  from  28.3  to  32.9  gallons.    The  average  is  about  31  gallons 
and  for  average  conditions  this  figure  may  be  close  enough  for  most 
purposes.      In  the  cases  of  the  dolomitic  lime  this  quantity  of  water  is 
considerably  less  and  averaged  for  the  two  samples  tested  24  gallons. 

(3)  The  weight  of  high  calcium  lime  in  a  cu.  ft.  of  putty  ranged 
from  38.6  to  45.2  Ibs.  and  averaged  41.4  Ibs.,  which  figure  is  probably 
a  satisfactory  one  to  use  on  the  job.     For  dolomitic  limes  the  average 
was  53.5  Ibs. 

(4)  The  weight  of  1  cu.  ft.  of  putty  made  from  high  calcium  lime 
varied  from  89.3  to  100.1  Ibs.  and  averaged  94.4  Ibs.  and  for  dolomitic 
limes  the  average  was  105.7  Ibs. 

In  order  to  make  this  point  more  clear  the  table  has  been  recal- 
culated, allowance  being  made  for  the  amount  of  water  which  enters 
into  chemical  combination  with  the  lime. 

HIGH   CALCIUM  LIME 


Sample  No. 

117 

114 

116 

118 

120 

113 

119 

115 

Av. 

Lbs.  CaO  in  bbl. 

183.2 

182.9 

182.9 

179.1 

176.2 

175.7 

175.5 

156.0 

(185  Ibs.  lime  net) 

Water  chemically 

combined      with 

lime,  Ibs. 

58.8 

58.7 

58.7 

57.5 

56.6 

56.5 

56.4 

50.1 

Free    water    in 

paste,  Ibs. 

186.2 

220.7 

214.9 

196.7 

213.5 

186.1 

217.8 

137.0 

Free  water  in  paste,  salt 

22.3 

26.5 

25.8 

23.6 

25.6 

22.3 

26.1 

16.4 

23.6 

DOLOMITIC   LIME 


Sample  No. 

121 

124 

Av. 

Lbs.  CaO  in  bbls.    (185  Ibs.lime  net) 
Water  chemically  combined  with 
lime,  Ibs. 
Free  water  in  paste,  Ibs. 
Free  water  in  paste,  gals. 

104.4 

33.5 
177.2 
21.2 

104.9 

33.7 
146.2 
17.5 

19.3 

The  first  line  gives  the  number  of  pounds  of  calcium  oxide  in  a 
barrel  of  lime  containing  185  pounds  net. 

The  second  line  gives  the  pounds  of  water  chemically  combined  with 
the  above  amount  of  calcium  oxide. 

Line  three  gives  the  pounds  of  free  water  in  the  paste. 

Line  four  gives  the  gallons  of  free  water  in  the  paste. 

An  inspection  of  this  table  shows  that  the  amount  of  free  water  in 
a  paste  made  from  high  calcium  lime  varies  from  16.4  gallons  to  26.5 
gallons  with  an  average  amount  of  23.6  gallons. 

The  amount  of  free  water  in  a  paste  made  from  dolomitic  lime  varies 
from  21.2  gallons  to  17.5  gallons  with  an  average  of  19.3  gallons. 

The  above  two  tables  illustrate  very  clearly  the  great  variation  in  the 
quantity  of  water  required  to  reduce  various  limes  to  a  workable  paste. 
Because  of  this  great  variation,  it  is  very  dLUcult  to  determine  in  advance 
the  amount  of  lime  which  is  present  in  a  mortar  made  from  lump  lime. 

LIME  "BURNED"  It  is  a  well  known  fact  that  wThen  quick  lime  is 
DURING  SLAKING  slaked  to  a  paste,  if  insufficient  water  is  used  the 
resulting  paste  is  not  so  plastic  and  works  short. 
This  condition  is  generally  spoken  of  as  "burning"  in  slaking.  Until 
very  recently,  no  scientific  reason  was  known  for  this  "burning"  of  lime 
during  slaking.  W.  E.  Emley,  of  the  U.  S.  Bureau  of  Standards,  in  a 
paper  presented  before  the  National  Lime  Manufacturers'  Association  in 
February  1914,  gave  the  first  explanation  of  this  "burning"  during  slak- 
ing with  which  the  writer  is  familiar.  According  to  Emley,  when  in- 
sufficient water  is  used  in  slaking,  the  temperature  of  the  mass  is  raised 
considerably  above  the  boiling  point  of  water,  and  at  this  elevated  tem- 
perature a  compound  is  formed  which  has  different  characteristics  than 
ordinary  calcium  hydroxide.  For  convenience  it  may  be  called  lime 
"burned"  during  slaking.  This  "burned"  compound  differs  chemically 
from  calcium  hydroxide  in  the  rapidity  with  which  it  absorbs  carbon  dioxide 
from  the  air,  this  reaction  being  so  rapid  that  it  is  practically  impossible 
to  weigh  the  material  on  the  ordinary  chemical  balance.  Physically  it 
differs  from  both  lime  and  hydrate  in  that  it  feels  gritty  and  has  a  slightly 
yellow  color.  Under  the  microscope  it  differs  optically  from  both  lime 


37 


and  hydrate.  These  chemical  and  physical  differences  show  that  the 
compound  formed  by  "burning"  in  slaking  is  neither  lime  nor  hydrate 
but  a  new  chemical  compound.  Since  the  material  has  not  been  isolated 
in  a  pure  state  it  is  therefore  impossible  to  assign  to  it  a  definite  formula; 
in  all  probability  it  is  an  oxy-hydrate.  It  has  been  shown  that  a  basic 
carbonate  of  lime  having  the  formula  2CaO .  CO2  can  be  formed,  also  the 
corresponding  hydrate  is  known  Ca(OH)2 .  CaCO3.  Arguing  from  these 
compounds,  the  probable  formula  for  the  so  called  oxy-hydrate  would 
be  CaO.Ca(OH)2. 

AGING  LIME  The  danger  of  "burning"  in  slaking  is  much  greater  with 
PASTE  high  calcium  limes  since  these  generate  the  greater  amount 

of  heat,  and  it  is  therefore  necessary  to  employ  a  large 
excess  of  water  and  to  see  that  all  the  lime  comes  in  contact  with  water. 
This  excess  of  water  lowers  the  temperature  both  by  absorbing  the  heat 
and  by  evaporation. 

Slaking  is  a  chemical  process  and  time  is  required  to  complete  the 
action;  hence,  it  is  necessary  to  allow  the  paste  to  age  for  some  time  to 
be  assured  of  complete  slaking.  All  lime  contains  some  over-burned 
particles,  or  particles  of  lime  which  have  united  chemically  with  the 
silica  or  clay  in  the  limestone,  and  these  particles  are  extremely  slow 
slaking,  often  requiring  days  and  weeks  to  become  thoroughly  satis- 
fied with  water.  Our  forefathers  recognized  this  fact  and  always  allowed 
the  lime  paste  to  age  for  weeks,  and  often  months,  before  using. 

The  necessity  of  aging  lime  paste  before  using  was  recognized  by 
the  Romans.  Vitruvius  gives  the  following  directions  for  the  prepara- 
tion of  lime  paste  to  be  used  in  plastering.*  "This  will  be  all  right  if  the 
best  lime,  taken  in  lumps,  is  slaked  a  good  while  before  it  is  to  be  used, 
so  that,  if  any  lump  has  not  been  burned  long  enough  in  the  kiln,  it  will 
be  forced  to  throw  off  its  heat  during  the  long  course  of  slaking  in  the 
water,  and  will  thus  be  thoroughly  burned  to  the  same  consistency.  When 
it  is  taken  not  thoroughly  slaked  but  fresh,  it  has  little  crude  bits  con- 
cealed in  it,  and  so,  when  applied,  it  blisters.  When  such  bits  complete 
their  slaking  after  they  are  on  the  building,  they  break  up  and  spoil  the 
smooth  polish  of  the  stucco. 

"But  when  the  proper  attention  has  been  paid  to  the  slaking,  and 
greater  pains  have  thus  been  employed  in  the  preparation  for  the  work> 
take  a  hoe,  and  apply  it  to  the  slaked  lime  in  the  mortar  bed  just  as  you 
hew  wood.  If  it  sticks  to  the  hoe  in  bits,  the  lime  is  not  yet  tempered; 
and  when  the  iron  is  drawn  out  dry  and  clean,  it  will  show  that  the  lime 
is  weak  and  thirsty;  but  when  the  lime  is  rich  and  properly  slaked,  it  will 
stick  to  the  tool  like  glue,  proving  that  it  is  completely  tempered." 

"Vitruvius,  translated  by  Morris  Hicky  Mo.-gan,  Cambridge,  Mass.,  1914,  page  204. 

38 


The  art  of  preparing  lime  mortar  of  the  finest  quality  has  survived 
in  Italy  to  this  day.    *"  So  late  as  1851  an  English  architect,  when  sketch- 
ing in  the  Campo  Santo  at  Pisa,  found  a  plasterer  busy  in  lovingly  repair- 
ing portions  of  its  old  plaster  work,  which  time  and  neglect  had  treated 
badly,  and  to  whom  he  applied  himself  to  learn  the  nature  of  the  lime 
he  used.    So  soft  and  free  from  caustic  qualities  was  it  that  the  painter 
could  work  on  it  in  true  fresco  painting  a  few  days  or  hours  after  it  was 
repaired,  and  the  modeler  used  it  like  clay.     But  until  the  very  day  the 
architect  was  leaving  no  definite  information  could  he  extract.    At  last, 
at  a  farewell  dinner,  when  a  bottle  of  wine  had  softened  the  way  to  the 
old  man's  heart,  the  plasterer  exclaimed,  'And  now,  signor^I  will  show 
you  my  secret!*     And  immediately  rising  from  the  table,  the  two  went 
off  into  the  back  streets  of  the  town,  when,  taking  a  key  from  his  pocket, 
the  old  man  unlocked  a  door,  and  the  two  descended  into  a  large  vaulted 
basement,  the  remnant  of  an  old  palace.    There  amongst  the  planks  and 
barrows,  the  architect  dimly  saw  a  row  of  large  vats  or  barrels.     Going 
to  one  of  them,  the  old  man  tapped  it  with  his  key;   it  gave  a  hollow 
sound  until  the  key  nearly  reached  the  bottom.      *  There,  signor!    There 
is  my  grandfather!     He  is  nearly  done  for.'      Proceeding  to  the  next, 
he  repeated  the  action,  saying,       'There,  signor,  there  is  my  father! 
There  is  half  of  him  left.'    The  next  barrel  was  nearly  full.    'That's  me!' 
exclaimed  he;   and  at  the  last  barrel  he  chuckled  at  finding  it  more  than 
half  full;    'That's  for  the  little  ones,  signor!'     Astonished  at  this  barely 
understood  explanation,  the  architect  learned  that  it  was  the  custom  of 
the  old  plasterers,  whose  trade  descended  from  father  to  son  from  many 
successive  generations,  to  carefully  preserve  any  fine  white  lime  produced 
by  burning  fragments  of  pure  statuary,  and  to  each  fill  a  barrel  for  his 
successors.     This  they  turned  over  from  time  to  time,  and  let  it  air- 
slake  in  the  moist  air  of  the  vault,  and  so  provide  pure  old  lime  for  the 
future  by  which  to  preserve  and  repair  the  old  works  they  venerated. 
After  inquiries  showed  that  this  was  a  common  practice  in  many  an  old 
town,  and  thus  the  value  of  old  air-slaked  lime,  such  as  had  been  written 
about  eighteen  hundred  years  before,  was  preserved  as  a  secret  of  the 
trade  in  Italy,  whilst  the  rest  of  Europe  was  advocating  the  exclusive 
use  of  newly  burnt  and  hot  slaked  lime." 

NECESSITY  FOR      If  a  good,  sound,  smooth  working  lime  paste  is  to  be 

HYDRATED  LIME    made  from  lump  lime,  it  is  absolutely  necessary  that 

the  lime  be  slaked  some  considerable  time  before  using. 

Compare  the  method  of  slaking  recommended  by  Vitruvius  and  that 

of  the  skilled  Italian  plasterer  with  the  modern  method  of  slaking  the 

lime  in  the  middle  of  a  ring  of  sand  and  almost  immediately  hoeing  in 

*Hodgson,  Concrete,  Cement,  Mortar,  Plaster  and  Stucco,  pages  22  to  25. 


the  sand.  In  the  present  practice  more  often  than  not,  the  plaster  is 
placed  on  the  wall  or  the  mortar  laid  between  the  bricks  within  a  few 
hours.  Such  mortar  must  contain  free  lime  that  has  not  had  time  or 
opportunity  to  slake.  This  lime  later  takes  up  water  causing  the  mortar 
to  be  crumbly  or  the  plaster  to  crack  and  pop. 

In  spite  of  improvements  in  the  method  of  producing  lime  with 
better  and  more  economical  kilns,  the  material  is  brought  into  the  mar- 
ket in  the  same  manner  as  it  was  centuries  ago.  Further,  the  method 
of  slaking  lime  has  changed  only  for  the  worse,  in  that  our  rapid  modern 
practice  does  not  admit  of  the  slow  action  of  slaking  lime  thoroughly 
on  the  operation. 

The  only  improvement  in  the  form  of  the  merchantable  lime,  known 
to  the  author,  is  that  of  hydrated  lime.  This  will  be  dealt  with  in  the 
next  chapter. 


40 


MANUFACTURE  OF  HYDRATED  LIME 


CHAPTER  VI 

WITHIN  recent  years  a  method  has  been  introduced  of  treating 
lime  with  water  in  a  suitable  apparatus  in  which  the  lime  com- 
bines with  sufficient  water  to  satisfy  the  chemical  requirements 
of  the  calcium  oxide  forming  a  dry,  finely  divided  flour,  the  so  called 
Hydrated  Lime.  Hydrated  lime  can  be  defined  as  the  dry  fiocculent  powder 
resulting  from  the  treatment  of  quick  lime  with  sufficient  water  to  satisfy  the 
calcium  oxide.  This  material  comes  into  the  market  in  bags  or  other 
convenient  packages  and  is  ready  for  use  requiring  only  gauging  with 
water  and  mixing  with  sand  in  much  the  same  manner  as  cement  is 
used.  The  fact  that  lime  could  be  slaked  to  the  form  of  a  dry  powder 
has  long  been  known,  and  three  methods  have  been  used  in  the  past  to 
produce  this  powder. 

METHODS  OF  1.  Lime,  in  comparatively  small  pieces  about  the  size 
DRY  SLAKING  of  an  egg,  is  placed  in  a  basket  and  immersed  in  water 
for  a  minute  or  two  until  hydration  has  commenced, 
when  it  is  withdrawn.  The  wet  lime  is  generally  put  in  heaps  or  silos  in 
order  to  conserve  the  heat  and  prevent  the  escape  of  the  vapor.  The 
material  swells,  cracks  and  becomes  reduced  to  a  dry  powder. 

2.  Lumps  of  lime  are  placed  in  a  heap  and  wetted  at  intervals  so 
that  the  mass  is  equally  moistened  throughout.     The  slaking  proceeds 
as  in  the  first  instance. 

3.  Small  pieces  of  lime  are  exposed  to  the  air  for  a  number  of 
months.    The  material  absorbs  both  water  and  carbon  dioxide  from  the 
atmosphere,  falling  to  a  dry  powder.    The  powdered  form  consists  of  a 
hydrated  sub-carbonate  of  lime  containing  about  10%  to  11%  of  water. 

These  methods  of  dry  slaking  lime  are  crude,  and  unless  the  greatest 
care  is  exercised,  the  resulting  dry  product  will  contain  particles  of  un- 
slaked lime.  Further,  the  hydrates  produced  by  these  methods  gen- 
erally work  short  and  possess  poor  sand  carrying  capacities;  in  fact, 
hydrated  lime  produced  by  any  of  the  above  methods  is  only  suitable 
for  use  on  the  soil,  and  such  hydrate  should  not  be  confounded  with 
hydrated  lime  manufactured  by  modern  methods. 

41 


MODERN  METHODS     The  modern  method  of  manufacturing  hydrated 

OF  HYDRATING  lime  depends  upon  the  addition  of  an  exact  amount 

of  water  to  a  pre-determined  exact  amount  of  lime. 

By  no  other  method  is  it  possible  to  produce  a  hydrate  which  will  contain 
sufficient  combined  water  to  satisfy  the  demands  of  the  calcium  oxide 
present.  It  is  important  that  all  the  calcium  oxide  be  in  combination 
with  water,  otherwise  the  hydrate  will  be  unsound  and  unsuitable  for 
many  uses.  This  point  will  be  insisted  upon  in  any  specifications  that 
may  be  drawn  for  hydrated  lime  to  be  used  in  the  building  trade.  It  is 
vital  for  each  manufacturer  to  recognize  the  fact  that  the  formation  of 
hydrated  lime  involves  a  chemical  change,  requiring  the  presence  of 
definite  amounts  of  lime  and  water.  Since  the  process  is  chemical,  it 
requires  the  same  careful  supervision  as  any  other  chemical  process, 
such  as  the  manufacture  of  Portland  cement. 

PIERCE  PROCESS  The  first  commercial  process  used  for  preparing  hy- 
drated lime  in  this  country  was  the  so-called  "  Pierce  " 
Process.  This  consisted  in  slaking  the  lime  to  a  wet  paste,  then  drying  the 
paste  so  as  to  expell  all  the  excess  moisture  over  and  above  that  needed 
for  the  chemical  requirements,  thereby  reducing  the  material  to  a  form 
that  could  be  ground.  If  the  process  was  carefully  carried  out,  a  good 
grade  of  hydrated  lime  was  produced.  This  method  has  been  abandoned 
owing  to  the  excessive  cost  of  manufacture. 

DODGE  PROCESS  The  second  method  employed  was  the  so-called 
"Dodge"  Process.  This  process  consisted  first  in 
grinding  the  lime  so  as  to  pass  a  26  mesh  sieve,  second  in  treating  a 
weighed  amount  of  the  ground  lime  with  sufficient  water  thoroughly  to 
satisfy  the  calcium  oxide  present  and  produce  a  dry  hydrate,  third  the 
dry  hydrate  was  sifted  through  fine  silk  cloth.  A  description  of  this 
method  is  given  in  the  "Engineering  News,"  Vol.  50,  Pages  177  to  179, 
August  27,  1903,  by  S.  Y.  Brigham.  In  this  article  it  is  stated  that  on 
the  average  high  calcium  limes  containing  97%  of  calcium  oxide  require 
about  55  pounds  of  water  to  100  pounds  of  lime,  while  dolomitic  limes 
require  only  36  pounds  of  water  to  100  pounds  of  lime  to  produce  a  good 
hydrate. 

From  these  two  pioneer  processes  have  been  evolved,  during  the 
last  fifteen  years,  the  methods  described  below  which  are  in  use  at  the 
present  time. 

CLYDE  PROCESS  A  weighed  quantity  of  ground  lime  is  fed  from  a 
hopper  directly  into  a  large  horizontal  pan.  This  pan 
is  so  mounted  that  it  can  be  rotated  around  its  vertical  axis,  and  there  are 
a  series  of  plows  arranged  to  turn  over  and  mix  the  material  in  the  pan. 
To  the  weighed  amount  of  lime  a  pre-determined  quantity  of  water  is 

42 


added  and  the  whole  mass  agitated  by  revolving  the  pan.  When  all  the 
water  needed  chemically,  has  been  taken  up,  and  the  excess  driven  off 
as  steam,  the  hydrated  lime  is  dumped  through  an  opening  in  the 
centre  of  the  pan.  It  is  customary  to  take  the  hydrate  directly  from 
the  pan,  and  store  it  in  bins  in  order  to  age  the  product.  The  dry 
hydrate  from  the  bins  is  either  screened  or  graded  by  means  of  air 
separation. 


CLYDE  HYDRATOR 

REANEY  PROCESS  A  weighed  amount  of  the  lime  is  introduced  into  the 
upper  end  of  a  cylinder,  which  is  slightly  inclined  from 
the  horizontal.  A  sufficient  amount  of  water  is  added,  and  the  material 
agitated  by  revolving  the  cylinder.  Inside  of  the  cylinder  there  are  a 
series  of  encircling  rings,  which  act  as  dams  to  retard  the  flow  of  the 
lime  toward  the  discharge  end.  The  lighter  particles  of  the  hydrate 
rise  and  pass  over  the  retarding  rings  while  the  heavier,  unhydrated 
particles  are  retained  until  the  hydration  is  complete.  The  lower  or 
discharge  end  of  the  cylinder  is  encircled  with  a  tapering  screen;  the  fine 
hydrated  particles  pass  through  this  screen,  and  are  removed.  The 
coarser  particles  which  pass  over  the  screen,  are  eitner  thrown  away  or 
returned  to  the  feed  end  of  the  hydrator  for  further  treatment. 

KRITZER  PROCESS     The  cracked  or  ground  lime  and  water  are  separately 
fed  into  the  upper  of  a  series  of  enclosed  cylinders 

(generally  4  or  6)  mounted  one  on  top  of  the  other.  The  amount  of 
lime  is  controlled  by  a  screw  feeding  device  and  the  quantity  of  water  is 
proportioned  by  a  needle  valve.  The  lime  and  water  are  propelled 
throughout  the  series  of  cylinders  by  means  of  paddles  mounted  on  a 
shaft  extending  through  each  cylinder;  these  shafts  being  rotated  by  gear- 
ing on  the  outside.  Both  materials  are  thus  carried  through  the  whole 
series  of  from  four  to  six  cylinders,  and  the  product  is  discharged  from 

43 


KRITZEK  HYDRATOR 


the  lower  or  last  cylinder  thoroughly  hydrated.  The  machine  is  also 
provided  with  a  stack  on  the  upper  cylinder,  and  openings  in  the  lower 
cylinder,  thus  a  draft  is  produced  through  the  cylinders  in  the  opposite 

direction  to  the  travel  of  the  lime. 

) 

LAUMAN  PROCESS      The  cracked  lime  is  fed  directly  into  an  inclined 
stationary  cylinder;  within  this  cylinder  are  paddles 

carried  on  a  shaft  which  feed  the  lime  forward  by  their  revolutions.  The 
water  is  added  through  a  pipe  in  the  upper  end  of  the  cylinder.  As  the 
material  is  gradually  fed  forward  it  becomes  mixed  with  w^ater  and  the 
hydration  takes  place.  The  quality  of  the  hydrate  is  judged  by  observ- 
ing the  material  discharged  from  the  cylinder. 

These  methods  are  in  commercial  use  today  and  a  good  grade  of 
hydrate  can  be  produced  by  any  of  the  methods  provided  sufficient  care 
is  taken  to  assure  the  addition  of  the  correct  amount  of  water  and  suf- 
ficient time  is  allowed  to  form  a  sound  hydrate.  It  is  the  general  custom 
either  to  screen  the  hydrate  or  to  pass  it  through  an  air  separating  system 
in  order  to  remove  particles  of  unhydrated  lime,  core  and  other  impurities. 
It  is  further  important  that  the  heat  generated  by  the  action  of  the  lime 
and  water,  be  removed  as  rapidly  as  possible  in  order  to  keep  the  tem- 
perature of  hydration  below  the  point  at  which  the  lime  "burns"  in 
slaking. 

IMPORTANT  FEATURES  In  any  method  of  hydrating  lime  an  excess  of 
IN  HYDRATING  water  is  used  over  and  above  that  required  to 

combine  chemically  with  the  lime.     This  excess 

water  is  driven  off  as  steam  by  the  heat  generated  in  slaking.  The 
quantity  of  water  required  is  subject  to  wide  variations,  since  it  is  de- 
pendent upon  a  number  of  conditions,  such  as  the  temperature  of  the 
water,  lime  and  the  atmosphere.  If  too  little  water  is  used,  some  particles 
of  lime  will  not  have  access  to  wrater  and  these  will  not  slake  but  will 
be  present  in  the  finished  hydrate,  causing  it  to  be  unsound.  Also  too 
little  water  results  in  the  production  of  a  hydrate  which  works  short, 
due  to  its  having  been  "burned"  in  slaking.  Too  much  water  results  in 
a  damp  or  wet  hydrate,  which  is  difficult  to  handle.  The  addition  of  the 
correct  amount  of  water  requires  the  most  careful  supervision  of  any  of 
the  operations  of  hydration  if  a  good  grade  of  hydrate  is  to  be  produced. 
This  part  of  the  operation  must  be  carefully  controlled  and  be  subjected 
to  checks  from  day  to  day. 


PROPERTIES  OF  HYDRATED  LIME 


CHAPTER  VII 


WATER  CONTENT  IN 
HYDRATED  LIME 


Hydrated  lime  is  a  fine  dry  powder  consisting 
essentially  of  calcium  hydrate  and  magnesium 
oxide.  The  amount  of  combined  water  contained 

in  the  hydrate  varies  directly  as  the  calcium  oxide  content.  Since  cal- 
cium oxide  is  the  only  compound  present  in  lime  which  possesses  the  prop- 
erty of  combining  with  water,  it  follows  that  the  greater  the  amount  of 
calcium  oxide  present  in  the  lime,  the  greater  will  be  the  amount  of  water 
required  to  combine  with  it.  A  more  complete  explanation  of  this  fact 
has  been  given  in  the  chapter  devoted  to  the  Chemistry  of  Lime. 
This  is  illustrated  by  the  table  given  below: 

Percent  of  calcium  oxide         Percent  of  calcium  oxide 
in  original  lime  in  hydrate 

100         (a)  75.675 

95         (b)  72.78 

58.34  (c)  49.12 

52         (d)  44.55 

(a) — Pure  high  calcium  lime 
(b) — High  calcium  lime  5%  impurities 
(c) — Pure  dolomitic  lime 
(d) — Impure  dolomitic  lime 

Pure  high  calcium  hydrate  contains  24.32%  of  combined  water, 
while  a  pure  dolomitic  hydrate  contains  only  15.78%.  As  the  amount  of 
impurities  (silica  and  clay)  increases,  the  amount  of  combined  water 
decreases.  This  may  be  seen  by  comparing  (b)  with  (a)  and  (d)  with 
(c)  in  the  above  table. 

CHEMICAL  COMPOSITION  OF     The  chemical  compositions  of  various  com- 
VARIOUS  HYDRATED  LIMES        mercial  hydrated  limes  are  given  below: 


Percent  of  water 
required  in  hydrate 

24.325 
23.08 
15.78 
14.33 


No. 

1* 

2* 

3* 

4* 

5** 

6* 

7* 

Silica 
Alumina 
Iron  Oxide 
Lime 
Magnesia 
Carbon  Dioxide 
Water 

.42 

!si 

72.25 
1.47 
.57 

24.98 

.97 
.29 
.33 
69.63 
4.11 
1.88 
22.56 

.95 
.50 
.51 
71.66 
.36 
1.80 
23.81 

1.23 
.42 

.18 
71.22 
1.88 
1.37 
23.76 

.96 
.63 
.13 
73.45 
.58 
.69 
23.97 

3.05 
.20 
.30 
48.76 
30.04 
.92 
16.32 

.24 

.22 
.06 
52.27 
28.96 

16]79 

73.72     73.74     72.02     73.10     74.03     78.80     81.23 


Combined  Oxides  ) 

CaO+MgO  (Calculated)  f 

1 — Maine  3 — Pennsylvania  5 — Washington  7 — Ohio 

2 — New  Jersey  4 — Alabama  6 — Michigan 

Numbers  1,  2,  3,  4  and  5  represent  high  calcium  hydrate. 

Numbers  6  and  7  represent  dolomitic  hydrate. 

*Analyses  from  Technologic  Paper  No.  16,  Manufacture  of  Lime,  Bureau  of  Standards. 
** Analysis  by  Author. 

46 


PHYSICAL  AND  CHEMICAL    In  1909  the  author  gave  a  table  showing  the 
CHARACTERISTICS  most  important  chemical  and  physical  char- 

acteristics of  hydrated  lime  to  the  National 
Lime  Manufacturers'  Association.    This  table  is  here  reproduced. 


DOLOMITIC  HYDRATES 

HIGH    CALCIUM 
HYDRATES 

1  —  Weight  per  cu.  ft.  loose 
2  —  Weight  per  cu.  ft.  shaken 
3  —  Specific  Gravity 
4  —  Residue  Insoluble  in  hydro- 
chloric acid 
5  —  Moisture 
6  —  Combined  water 
7  —  Carbon  Dioxide 
8  —  Available  Oxide 

30.40     31.72     37.20     36.30 
36.40     36.23    42.40     45.10 
2.50       2.53       2.41       2.50 

.40%     .40%     .24%     .28% 
.30         .00         .35         .00 
17.22     15.88     18.07     17.29 
.75         .30         .41         .17 
80.38     83.02     80.47     82.03 

35.70     35.80 
41.20    45.30 
2.16       2.07 

.25%     .33% 
.00         .00 
24.52     24.37 
.54         .15 
74.00     74.96 

Referring  to  the  table,  the  horizontal  line  1  gives  the  weight  per 
cubic  foot,  loose. 

Line  No.  2  gives  the  weight  per  cubic  foot,  shaken. 

Line  No.  3  gives  the  specific  gravity — this  is  obtained  by  dividing  the 
weight  of  the  substance  by  the  weight  of  the  same  volume  of  water.  It  is, 
therefore,  a  measure  of  density,  and  gives  the  relative  weight  of  the  unit 
volume  of  the  material  as  compared  to  the  weight  of  unit  volume  of  water. 
The  higher  specific  gravity  of  the  dolomitic  hydrate  is  due  to  the  fact 
that  only  the  lime  present  in  the  calcined  dolomite  combines  with  water, 
the  magnesia  being  present  as  the  oxide.  From  the  specific  gravity  and 
the  weight  per  cubic  foot  of  any  material  it  is  possible  to  calculate  the 
amount  of  voids  or  the  space  occupied  by  the  air.  Assume  the  specific 
gravity  of  a  hydrate  to  be  2.50  and  the  weight  to  be  40  Ibs.  to  the  cubic 
foot.  The  specific  gravity  means  that  a  cubic  foot  of  perfectly  solid 
hydrate  weighs  2.50  times  as  much  as  a  cubic  foot  of  water.  A  cubic 
foot  of  water  weighs  62.4  Ibs.,  then  a  cubic  foot  of  hydrate  (perfectly 
solid  containing  no  voids)  would  weigh  62.4  X  2.50  =  156  Ibs.  The 
hydrate,  however,  weighed  only  40  Ibs.  per  cubic  foot,  therefore  the  air 
occupied  a  space  equal  to  such  a  volume  of  hydrate  as  would  weigh 
(156-40  =  116)  116  Ibs.  The  per  cent  of  voids  would  be  116/156  =  74.4%. 

Line  No.4  is  the  residue  insoluble  in  dilute  hydrochloric  acid  (muriatic 
acid)  and  consists  of  sand,  clay,  or  ashes  present  in  the  hydrated  lime.  In 
every  case  (except  in  hydraulic  hydrates)  this  is  inert  material  and  has 
no  value  as  a  binding  agent;  it  should,  therefore,  be  looked  upon  as  an 
impurity  and  in  case  the  amount  is  over  2%  it  would  materially  injure 
the  sand  carrying  capacity  of  the  hydrate. 

47 


Line  No.  5  gives  the  amount  of  water  present  as  free  (or  mechanically 
contained)  moisture  and  not  combined  with  the  lime.  This  should  be 
present  only  in  small  quantities.  If  too  great  an  excess  of  water  is 
present  the  hydrate  will  have  a  tendency  to  lump  or  cake. 

Line  No.  6  gives  the  amount  of  water  which  has  entered  into  chem- 
ical combination  with  the  lime  to  form  the  hydrate  and  which  is  a  neces- 
sary and  important  ingredient.  The  amount  should  always  be  sufficient 
to  satisfy  all  the  calcium  oxide  present.  Attention  has  been  called  to  the 
fact  that  the  amount  of  combined  water  is  always  greater  in  the  high 
calcium  hydrates. 

Line  No.  7  gives  the  carbon  dioxide  (carbonic  acid  gas)  present  in 
the  hydrate.  This  gas  is  in  combination  with  the  lime  and  denotes  either 
the  presence  of  unburned  limestone  (core)  or  that  the  hydrate  has  taken 
up  carbonic  acid  from  the  atmosphere;  in  any  case  the  amount  present 
should  be  small,  less  than  2%,  otherwise  it  indicates  an  inferior  hydrate. 
The  lime  already  combined  with  carbonic  acid  is  inert  and  unable  to 
contribute  any  strength  to  the  mortar. 

Line  No.  8 :  in  this  horizontal  line  the  amount  of  caustic  oxides  present 
has  been  calculated,  that  is,  the  amount  of  bonding  material  which  is  capable 
of  uniting  with  the  carbonic  acid  of  the  atmosphere  thereby  producing 
the  bond  of  the  mortar.  This  is  deduced  by  subtracting  from  100  the 
residue  insoluble  in  hydrochloric  acid  (4),  moisture  (5),  combined 
water  (6)  and  the  amount  of  calcium  carbonate  corresponding  to  the 

C(7)X100    ) 
amount  of  carbonic  acid  present  in  the  hydrate  <  - 

The  numbers  in  parenthesis  refer  to  the  horizontal  lines  in  the 
preceding  table. 


48 


USE  OF  HYDRATED  LIME  IN  SAND 
MORTARS 

CHAPTER  VIII 

IT  may  be  stated  that  hydrated  lime  is  suitable  for  any  use  in  the 
building  trade  to  which  lump  lime  can  be  put.  This  in  general 
includes  its  use  in  mortars  and  plasters  aH44lrWouId  appearthttt-fts 
thejnaterial^becQmes  better  known,  its  advantages  will  be  found  to 
outweigh  any  disadvantages. 

A  i^tftar  made  with  hydrated  lime  often  does  not  trowel  quite  so 
easily  as  a  mortar  made  from  lime  putty.  The  smooth  working  qualities 
of  the  hydrate  can  be  greatly  improved  by  proper  method  of  manufac- 
turing and  by  allowing  the  mortar  or  paste  to  soak  over  night  so  that  the 
gauging  water  becomes  thoroughly  incorporated.  The  great  ease  of 
handling  hydrate  and  the  thoroughness  with  which  it  has  been  slaked 
make  up  to  a  great  extent  for  any  lack  of  plasticity. 

The  use  of  hydrated  lime  does  away  with  the  necessity  of  slaking 
lime  to  a  paste,  thus  saving  the  cost  of  slaking.  It  is  estimated  that  it 
costs  25  cents  a  barrel  to  slake  lime  in  a  mortar  box.  Hydrated  lime  comes 
into  the  market  in  convenient  packages  of  a  definite  weight.  This  makes 
it  possible  to  proportion  the  mortar  so  as  to  have  exact  quantities  of  lime 
and  sand  present,  a  fact  which  is  always  appreciated  both  by  the  archi- 
tect and  engineer.  It  is  much  more  difficult  to  obtain  accurate  propor- 
tions of  lime  and  sand  when  lump  lime  is  used,  especially  as  it  is  a  general 
custom  to  add  as  much  sand  as  possible  with  the  result  that  the  mortar 
is  often  over-sanded  and  possesses  little  strength. 

ADVANTAGES  OF  In  June,  1910,  the  author  presented  the  results 
HYDRATED  LIME  obtained  from  an  extended  series  of  tests  on  mortars 
made  from  both  hydrated  and  lump  lime,  to  the 
American  Society  for  Testing  Materials.*  One  of  the  most  important 
conclusions  drawn  from  these  investigations  was  that  the  mortar  produced 
from  hydrated  lime  was  stronger  than  that  produced  from  the  correspond- 
ing lump  lime  slaked  to  a  paste.  This  conclusion  was  to  be  expected, 
since  it  is  possible  to  manufacture  hydrated  lime  by  mechanical  means 
under  good  chemical  control,  which  is  more  thoroughly  slaked  than  it  is 
possible  to  slake  lump  lime  on  the  job.  The  user  in  dealing  with  hydrated 
lime  is  handling  a  product  which  can  be  definitely  proportioned  and  will 
*Proceedings  American  Society  for  Testing  Materials,  1910. 

49 


produce  known  results.  The  quality  of  hydrate  desired  can  be  specified 
in  advance  and  the  material  can  be  inspected  and  tested  (see  specifica- 
tion for  hydrate,  page  84)  in  order  to  determine  if  it  fulfills  the  require- 
ments. »  The  quality  of  quicklime  can  also  be  specified  and  its  character 
determined  by  tests,  but  such  tests  do  not  indicate  what  will  be  the 
quality  of  mortar  found  on  the  job,  since  lime  is  chemically  changed 
during  slaking.  Hydrated  lime  undergoes  no  further  change  upon  the 
addition  of  water,  therefore  the  same  material  is  tested  which  is  to  be 
used.  The  testing  of  hydrated  lime  is  no  more  difficult  than  the  testing 
of  cement.  With  lump  lime  the  user  is  dependent  always  upon  the 
thoroughness  of  slaking  and  it  is  well  known  that  unless  the  paste  is 
run  off  and  stored  for  some  considerable  time,  there  is  no  assurance  of 
complete  and  thorough  slaking. 

Practically  all  those  who  investigated  the  strength  of  lime  mortars 
have  recommended  the  use  of  hydrated  lime  rather  than  lump  lime. 
In  Circular  No.  30, 1911  of  theBureau  of  Standards,  the  following  statement 
is  made:  "The  proportion  of  impurities  in  hydrated  lime  is  generally 
less  than  that  in  the  lime  from  which  it  is  made.  In  building  operations 
hydrated  lime  may  be  used  for  any  purpose  in  place  of  lump  lime,  with 
precisely  similar  results.  The  consumer  must  pay  the  freight  on  a  large 
amount  of  water,  but  the  time  and  labor  required  for  the  slaking  is 
eliminated  and  there  is  no  danger  of  spoiling  it  either  by  burning  or  in- 
complete slaking  *  *  *.  For  all  building  purposes  hydrated  lime 
is  to  be  preferred  to  lump  lime.  By  its  use  the  time  and  labor  involved 
in  slaking  may  be  saved  and  the  experience  of  the  laborer  is  eliminated 
as  a  factor  in  the  problem."  From  the  above  it  will  be  seen  that  those 
who  have  carefully  investigated  hydrated  lime  are  firm  in  their  opinion 
that  it  is  safer  and  superior  to  lump  lime. 

In  the  past  when  lump  lime  was  used  almost  exclusively  for  plaster- 
ing, it  was  the  practice  to  slake  the  lime  and  allow  it  to  season  for  some 
considerable  time  before  using  in  order  that  the  plaster  should  contain 
no  particles  of  quicklime.  This  occasionally  caused  delay  in  the  con- 
struction of  buildings.  Moreover,  plaster  made  from  lime  does  not  set 
quite  so  rapidly  or  in  the  same  manner  as  gypsum  plaster.  These  two 
points  have  led  people  to  believe  that  buildings  plastered  with  hydrated 
lime  are  delayed  in  the  course  of  construction.  By  the  use  of  hydrated 
lime  the  delay  due  to  slaking  and  seasoning  is  done  away  with,  and  by  a 
proper  method  of  planning  and  rotating  the  work,  the  job  can  be  com- 
pleted without  delay. 

50 


SECOND  NATIONAL  BANK  BUILDING,  TOLEDO,  OHIO 

D.  H.  BURNHAM  £  Co.,  CHICAGO,  ILL.,  ARCHITECTS 

Hydrated  Lime  Plaster  Used  Throughout  for  Scratch,  Brown  and  Finish  Coats 


SELECTION  In  the  preparation  of  mortar  or  plaster,  generally  little  atten- 
OF  SAND  tion  is  paid  to  the  quality  of  the  sand  employed.  Since  the 
sand  forms  three-quarters  or  more  of  the  mortar,  it  follows 
that  the  strength  is  largely  dependent  upon  the  quality  of  the  sand  used. 
Sand  for  use  in  lime  mortars  should  be  clean,  free  from  dirt  and  loam, 
and  as  coarse  as  is  consistent  with  the  character  of  surface  desired. 

Investigations  of  sands  have  shown  that  coarse  sand  yields  a  stronger 
mortar  than  fine  sand.  It  is  better  to  use  as  coarse  sand  as  possible  if  a 
strong  mortar  is  desired.  This  is  particularly  the  case  in  mortars  used 
in  brick  work  where  the  joints  between  the  bricks  are  wide.  The  grada- 
tion of  the  sand  grains,  that  is,  the  amount  of  the  different  sized  grains 
present,  should  be  such  as  to  give  the  greatest  density  or  the  least  voids 
in  the  sand.  The  following  specifications  for  a  mortar  sand  are  taken 
from  Bulletin  No.  70,  University  of  Illinois: 

"The  sand  shall  consist  of  grains  of  hard,  tough,  durable  rock  and 
must  be  free  from  soft,  decayed  or  friable  material. 

"The  suspended  matter  shall  not  exceed  6%  by  weight. 

"Not  more  than  15%  by  weight,  including  the  suspended  matter, 
shall  pass  a  No.  100  screen  nor  more  than  80%  a  No.  16  screen. 

"The  voids  shall  not  exceed  35%  of  the  total  volume." 

SAND-CARRYING  The  statement  is  often  made  that  hydrated  lime  will 
CAPACITY  OF  not  carry  so  much  sand  as  lime  paste.  This  is  really 
HYDRATED  LIME  not  the  case.  It  is  not  to  be  expected  that  200  pounds 
of  hydrated  lime  will  carry  as  much  sand  as  200  pounds 
of  lump  lime  slaked  to  a  paste  for  the  simple  reason  that  200  pounds 
of  hydrate  contains  less  calcium  and  magnesium  oxides  than  the  paste 
resulting  from  slaking  200  pounds  of  lump  lime.  By  referring  to  the 
equation  for  slaking  lime  on  page  15,  it  will  be  seen  that  56  pounds  of 
pure  high  calcium  lime  gave  74  pounds  of  hydrate;  therefore,  200  pounds 
of  lime  would  give  (56:74  =  200  :X)  264  pounds  of  dry  hydrate.  Thus 
264  pounds  of  hydrated  lime  contains  the  same  amount  of  calcium  and 
magnesium  oxide  as  200  pounds  of  lump  lime  slaked  to  a  paste.  It 
would  require  264  pounds  of  hydrate  to  carry  the  same  amount  of  sand 
as  200  pounds  of  lump  lime. 

MACHINE  MIXED    Within  the  last  few  years  machines  have  been  placed 
MORTAR  on  the  market  to  mix  the  sand  and  lime,  these  machines 

being  similar  in  operation  to  a  concrete  mixer.  By 
the  use  of  such  machines,  it  is  possible  to  mix  the  lime  and  sand  more 
thoroughly  and  the  mixing  is  accomplished  in  less  time  than  is  required 
by  hand.  Hydrated  lime  is  especially  adapted  for  use  in  the  mortar 
mixer  because  the  material  comes  on  the  work  in  a  convenient  form  and 
in  packages  of  known  weight. 

52 


On  a  recent  job  with  which  the  author  is  familiar,  all  the  mortar 
used  in  the  brick  work  was  mixed  in  this  manner.  The  mixing  machine 
was  operated  only  during  the  last  few  hours  in  the  afternoon,  enough 
mortar  being  prepared  for  next  day's  requirements.  The  mortar  mixed 
in  the  machine  was  dumped  into  the  basement  in  a  pile  and  was  allowed 
to  age  over  night.  When  used  the  mortar  was  entirely  satisfactory  and 
worked  free  and  smooth. 

PROPORTIONS  OF    Below  are  indicated  the  approximate  proportions  of 
MATERIALS  hydrate  and  sand  to  be  employed  in  mortar  for  various 

uses.  It  is  not  possible  to  give  specifications  covering 
all  conditions,  since  different  hydrates  will  carry  varying  quantities  of 
sand  and  more  particularly  because  the  character  of  the  sand  materially 
influences  the  quantity  of  hydrate  required. 


PROPORTIONS  FOR  HYDRATED  LIME  PLASTER* 

WOOD  LATH— THREE  COAT  WORK 

The  following  are  the  proportions  in  which  materials  should  be  mixed 
at  the  mixing  plant  or  by  the  contractor  on  the  job: 

PER  TON  OF  PER  HUNDRED  POUNDS  OF 

SANDED  PLASTER  HYDRATED  LIME 

SCRATCH  COAT 

1550  pounds  sand  350  pounds  sand 

450  pounds  hydrated  lime  100  pounds  hydrated  lime 

3J/2  pounds  hair  %  pound  hair 

BROWN  COAT 

1600  pounds  sand  400  pounds  sand 

400  pounds  hydrated  lime  100  pounds  hydrated  lime 

13/2  pounds  hair  %  pound  hair 

FINISH  COAT,  WHITE 
Lime  putty  properly  gauged  with  Plaster  of  Paris 

SAND  FLOAT  FINISH 

1450  pounds  sand  275  pounds  sand 

550  pounds  hydrated  lime  100  pounds  hydrated  lime 

*These  are  average  mixtures  for  first  class,  clean,  sharp  plastering  sand. 
Mixtures  may  be  changed  to  meet  other  qualities  of  sand. 

53 


WOOD  LATH— TWO  COAT  WORK 

PER  TON  OF  PER  HUNDRED  POUNDS  OF 

SANDED  PLASTER  HYDRATED  LIME 

FIRST  COAT 

1550  pounds  sand  350  pounds  sand 

450  pounds  hydrated  lime  100  pounds  hydrated  lime 

3j^  pounds  hair  %  pound  hair 

FINISH   COAT,  WHITE 
Lime  putty  properly  gauged  with  Plaster  of  Paris 

SAND  FLOAT  FINISH 

1450  pounds  sand  275  pounds  sand 

550  pounds  hydrated  lime  100  pounds  hydrated  lime 

METAL  LATH— THREE  COAT  WORK 

PER  TON  OF  PER  HUNDRED  POUNDS  OF 

SANDED  PLASTER  HYDRATED  LIME 

SCRATCH    COAT 

1550  pounds  sand  350  pounds  sand 

450  pounds  hydrated  lime  100  pounds  hydrated  lime 

4  pounds  hair  1  pound  hair 

BROWN    COAT 

1600  pounds  sand  400  pounds  sand 

400  pounds  hydrated  lime  100  pounds  hydrated  lime 

l*/2  pounds  hair  Yi  pound  hair 

FINISH   COAT,  WHITE 
Lime  putty  properly  gauged  with  Plaster  of  Paris 

SAND  FLOAT  FINISH 

1450  pounds  sand  275  pounds  sand 

550  pounds  hydrated  lime  100  pounds  hydrated  lime 

BRICK  OR  TILE— THREE  COAT  WORK 

PER  TON  OF  PER  HUNDRED  POUNDS  OF 

SANDED  PLASTER  HYDRATED  LIME 

SCRATCH  COAT 

1600  pounds  sand  400  pounds  sand 

400  pounds  hydrated  lime  100  pounds  hydrated  lime 

\Yl  pounds  hair  %  pound  hair 

BROWN    COAT 

1600  pounds  sand  400  pounds  sand 

400  pounds  hydrated  lime  100  pounds  hydrated  lime 

FINISH   COAT,  WHITE 
Lime  putty  properly  gauged  with  Plaster  of  Paris 

SAND  FLOAT  FINISH 

1450  pounds  sand  275  pounds  sand 

550  pounds  hydrated  lime  100  pounds  hydrated  lime 

54 


BRICK  or  TILE— TWO  COAT  WORK 

PER  TON  OF  PER  HUNDRED  POUNDS  OF 

SANDED  PLASTER  HYDRATED  LIME 

FIRST   COAT 

1600  pounds  sand  400  pounds  sand 

400  pounds  hydrated  lime  100  pounds  hydrated  lime 

1^2  pounds  hair  Y%  pound  hair 

FINISH    COAT,    WHITE 
Lime  putty  properly  gauged  with  Plaster  of  Paris 

SAND  FLOAT  FINISH 

1450  pounds  sand  275  pounds  sand 

550  pounds  hydrated  lime  100  pounds  hydrated  lime 

ON  CONCRETE 

100  pounds  sand 

800  pounds  hydrated  lime 

250  pounds  calcined  plaster 

WOOD  LATH,  BRICK  OR  TILE— ONE  COAT  W'ORK 

1550  pounds  sand 
450  pounds  hydrated  lime 
3J/2  pounds  hair 

GYPSUM  BLOCK— THREE  COAT  WORK 
Use  the  same  quantities  as  shown  for  Brick  or  Tile. 

NOTE — Mixtures  specified  on  pages  53,  54  and  55  are  average  mixtures  for  first  class, 
clean,  sharp  plastering  sand.   Mixtures  may  be  changed  to  meet  other  qualities  of  sand. 

HAND  MIXED     In  preparing  these  mortars,  the  best  and  most  economical 
MORTARS  results  will  be  obtained  by  the  use  of  a  mortar  mixing 

machine,  several  of  which  are  on  the  market.  If  hand 
mixing  is  to  be  used,  two  methods  may  be  employed  in  preparing  the 
mortar. 

FIRST — Soak  the  hydrate  with  water  so  as  to  produce  a  thick  paste, 
and  allow  to  stand  over  night,  then  add  the  desired  amount  of  sand  and 
sufficient  water  to  give  the  required  consistency  to  the  mortar.  It  is 
generally  conceded  that  this  method  produces  the  more  plastic  mortar. 

SECOND — Mix  the  hydrate  and  sand  dry,  the  same  as  with  cement 
mortar,  then  add  the  water  to  produce  the  required  consistency. 

55 


When  hair  is  used,  it  should  always  be  well  soaked  and  beaten  before 
mixing  with  the  mortar.  Thorough  hoeing  and  mixing  always  improves 
the  plasticity  and  working  qualities  of  a  mortar. 

LIME-CEMENT  MORTARS 

In  many  cases  where  a  mortar  having  a  greater  strength  is  required, 
or  it  is  advisable  to  have  considerable  strength  produced  quickly,  it  is 
advantageous  to  use  Portland  cement  in  the  mixture. 

Investigations  by  various  authorities  have  proven  the  fact  that 
hydrated  lime  and  Portland  cement  can  be  mixed  in  any  proportions 
from  an  addition  of  10%  of  hydrate  to  the  Portland  cement  for  making 
a  cement  mortar  to  an  addittion  of  10%  of  Portland  cement  to  the 
hydrate  for  making  a  hydrated  lime  mortar.  The  addition  of  hydrated 
lime  to  a  cement  mortar  improves  the  plasticity  and  water  tightness, 
and  the  addition  of  Portland  cement  to  a  hydrated  lime  mortar  increases 
the  early  time  strength. 

STRENGTH  OF  From  the  results  obtained  by  many  investigations  it 
CEMENT-LIME  may  be  stated  that  the  replacement  of  25%  of  Portland 
MORTARS  cement  with  hydrate  in  mortar  does  not  materially 

weaken  the  mortar.     Mr.  Emley*  from  his  investiga- 
tion drew  the  following  conclusion : 

"1.  While  the  strength  does  decrease  with  increasing  proportions 
of  lime,  samples  containing  25%  lime  are  not  very  much  weaker  than 
those  made  of  cement.  2.  High  calcium  lime  sets  more  rapidly  than 
dolomitic  lime.  Specimens  containing  the  former  are  therefore  stronger 
when  7  days  old.  Those  containing  dolomite  were  almost  as  strong  at 
28  days  and  at  3  months  had  just  about  caught  up  to  the  high  calcium 
limes.  3.  Samples  stored  under  water  set  more  slowly  than  those  stored 
in  air,  and  were  therefore  weaker  at  7  days.  But  at  3  months  those 
stored  under  water  were  much  the  stronger,  frequently  showing  twice 
the  strength  of  the  specimens  stored  in  air.  This  applies  equally  to  all 
specimens  containing  25%  or  less  of  lime,  whether  dolomitic  or  high 
calcium." 

Following  will  be  found  the  results  obtained  from  an  extended 
series  of  tests  made  under  the  direction  of  Prof.  Ira  H.  Woolson  of 
Columbia  University,  N.  Y.** 

The  charts  on  pages  57  to  60  clearly  illustrate  the  greater  strength 
developed  by  mortars  made  with  hydrated  lime  over  those  made  from 
the  corresponding  quick  lime  slaked  to  a  paste.  The  curves  plotted 
were  obtained  by  averaging  the  results  on  similar  tests  of  three  different 
hydrated  limes  and  three  different  quick  limes. 

*The  use  of  hydrated  lime  in  a  Portland  cement  mortar,  by  Warren  E.  Emley  and  H. 
P.  Greenwald,  Proceedings,  National  Lime  Manufacturers  Association,  1913. 

"""Comparative  Test  of  Lime  Mortar,  both  in  tension  and  compression,  by  E.  W.  Lazell, 
Proceedings  of  American  Society  for  Testing  Materials,  Page  328,  1910. 

56 


Tension  Tests  Average,  1  to  3  Mixture. 


r    .85  Cement,    ^i        f    .50  Cement 
t      ,15  Lime,      J       1      .50  Lime, 
3  Sand.  3  Sand. 


1  Lime, 
3  Sand. 


Quick-  Hy-  Quick-  Hy-  Quick-  Hy- 

lime.  drate.        lime.  drate.        lime.  drate. 

28  days 288  365           103           176           37  83 

3  months....      352  399.5       127  225           43  99 

12  months 502  517  174  267  81  125 

Percentage  of  Hydrated  Lime  is  by  weight  of  Portland  cement 


57 


Compression  Tests  Average,  1  to  3  Mixture. 


(    .85  Cement,  ) 
1      .15  Lime,      j 

J   .50  Cement,   \ 
t     .50  Lime,     j 

1  Lime, 

3  Sand. 

3  Sand. 

3  Sand. 

- 

Quick- 

Hy- 

Quick- 

Hy- 

Quick- 

Hy- 

lime. 

drate. 

lime. 

drate. 

lime. 

drate. 

28 

davs  . 

1,999 

2,170 

704 

858 

230 

210 

a 

"•*  j  • 
months  .  . 

.  .    2,451 

2,810 

859 

1,132 

199 

677 

12 

months.  . 

.  .    4,001 

4,263 

1,837 

2,116 

273 

840 

Percentage  of  Hydrated  Lime  is  by  weight  of  Portland  cement 


58 


Tension  Tests  Average,  1  to  5  Mixture. 

65  Cement.  .35  Lime.          1  Lime,  5  Sand. 

5  Sand. 

Quicklime.    Hydrate.  Quicklime.    Hydrate. 

28  days .          99  214  33  36 

3  months    ...        112  316  48  60 

12  months .  160  277  67  93 

Percentage  of  Hydrated  Lime  is  by  weight^of^Portland  cement 


59 


COMPRESSION 


SQO 


7SC 


ZB-D 


J-M< 


28  days  

3  months.  . 
12  months.  . 


Compression  Tests  Average,  1  to  5  Mixtures. 


.65  Cement,  .35  Lime.     1  Lime,    5  Sand. 

5  Sand. 

Quicklime.    Hydrate.    Quicklime.    Hydrate. 
.  "      574  1,339  126  175 

642  1,801'  150  316 

1,422  3,338  343  565 


Percentage  of  Hydrated  Lime  is  by  weight  of  Portland  cement 


60 


EQUITABLE  BUILDING,  NEW  YORK  CITY 

R.  E.  GRAHAM,  CHICAGO,  ARCHITECT 

Hydrated  Lime  Used  Throughout  in  All  Brick  Mortar 


It  is  often  stated  that  lime  made  from  dolomite  is  unsuitable  for 
use  in  connection  with  Portland  cement  because  of  the  high  magnesia 
content.  This  is  not  the  fact  as  is  shown  by  the  results  given  in  the  charts, 
since  these  cover  tests  made  on  both  high  calcium  and  dolomitic  limes. 
It  may  be  stated  that  the  magnesia  contained  in  dolomitic  limes  shows  no 
deleterious  action  but  on  the  contrary  is  a  valuable  ingredient  and  con- 
tributes to  the  strength  of  the  mortars. 

Proportions  for  hydrated  lime-cement  mortar,  proportions  being 
given  by  weight: 

BRICK  MORTAR 

THREE  TO  ONE  MIXTURE — Four  bags  Portland  cement,  one  bag 
(100  Ibs.)  hydrated  lime*  and  1,500  pounds  sand. 

FOUR  TO  ONE  MIXTURE — Three  bags  Portland  cement,  one  bag 
(100  Ibs.)  hydrated  lime*  and  1,600  pounds  sand. 

FIVE  TO  ONE  MIXTURE — Two  bags  Portland  cement,  one  bag 
(100  Ibs.)  hydrated  lime*  and  1,500  pounds  sand. 

STAINLESS  CEMENT  MORTAR — 300  pounds  white  cement,  100  pounds 
hydrated  lime  and  1,200  pounds  sand. 

FOR  TILE  SETTING  OR  ROOFING  TILE — 85%  of  Portland  cement, 
15%  of  hydrated  lime  used  with  3  parts  sand. 

CEMENT-HYDRATED  LIME  MORTAR  FOR  INTERIOR  PLASTERING  ON- 
BRICK  OR  TERRA  COTTA: 

SCRATCH  COAT  (OR  FIRST  COAT) — One  bag  Portland  cement,  2 
bags  (200  Ibs.)  hydrated  lime  and  1,200  pounds  sand. 

BROWN  COAT  (OR  SECOND  COAT) — One  bag  Portland  cement,  2 
bags  (200  Ibs.)  hydrated  lime  and  1,200  pounds  sand. 

CEMENT  MORTARS  FOR  FIREPROOFING  PARTITIONS — 100  pounds 
hydrated  lime  to  400  pounds  Portland  cement,  and  1,500  pounds  sand. 


*Hydrated  lime  is  usually  sold  in  100  ll>.  burlap  or  cotton  sacks  and  40  or  50  Ib.  paper 
sacks. 


USE  OF  HYDRATED  LIME  IN  CONCRETE 


CHAPTER  IX 

PLASTICITY  OF  During  the  time  of  mixing  and  placing  concrete  and 
HYDRATED  LIME  up  to  the  time  of  beginning  of  the  hardening,  concrete 
may  be  considered  as  a  plastic  material.  The  term 
plastic  as  used  in  reference  to  concrete  and  mortar  may  be  denned  as  that 
property  which  allows  the  material  to  be  cast  or  moulded  into  shape.  The 
plastics  differ  from  most  materials  of  construction  in  that  their  strength 
and  structural  integrity  depend  to  a  much  greater  extent  on  the  skill  of 
the  user  than  upon  that  of  the  manufacturer.  For  example,  the  quality 
of  concrete  is  much  more  dependent  on  the  quality  of  stone,  sand  and 
workmanship  than  on  the  quality  of  Portland  cement.  In  a  treatise  of 
this  kind  it  is  impossible  to  discuss  in  detail  how  the  hardening  of  the 
cement  is  affected  by  the  character  of  the  sand  and  stone  and  the  method 
of  mixing  and  placing.  It  will  be  readily  recognized  that  the  quality  of 
the  concrete  is  largely  dependent  upon  its  plasticity — or  the  ease  with 
which  the  plastic  mass  of  stone,  sand,  water  and  cement  will  flow  into 
place  and  assume  its  final  form.  This  being  the  case,  anything  which 
will  improve  the  plastic  quality  of  the  wet  mass  without  materially 
decreasing  its  strength  after  hardening  will  be  found  advantageous. 

VALUE  IN  MORTARS      The  value  of  concrete  and  mortars  in  construction 

AND  CONCRETE  work  depends  upon  the  ease  of  manipulating  them 

in  a  plastic  state  supplemented  by  the  quality  of 

subsequent  hardening  to  a  stone-like  mass.  It  is  possible  to  increase  the 
plasticity  by  using  an  excess  of  water,  and  this  is  commonly  done.  Two 
defects  are  introduced  by  the  use  of  too  much  water.  1st.  There  is 
great  danger  of  a  separation  between  the  stone  and  mortar  (sand  and 
cement)  if  the  mixture  is  too  wet,  resulting  in  weak  stratified  concrete. 
2nd.  The  excess  water  over  and  above  that  required  by  the  cement 
must  be  expelled  in  part  by  gravity  and  in  part  by  evaporation.  Since 
the  original  water  occupies  space,  it  follows  that  its  removal  results  in 
voids  and  a  non-dense  concrete.  In  large  slabs  the  loss  of  the  water  may 
cause  shrinkage  and  cracks.  The  addition  of  a  large  amount  of  excess 
water,  wrhile  it  makes  the  cement  mass  easier  to  pour,  always  results  in 
a  lack  of  density,  thereby  producing  a  weak  concrete. 

63 


"1  "ll  SB  «a  s 
89  sill  IS  II 
as  a 


£L 


LEADER-NEWS  BUILDING,  CLEVELAND,  OHIO 

CHAS.  A.  PLATT,  ARCHITECT 
Hydrated  Lime  Used  in  All  Concrete  and  Brick  Mortar 


INCREASED  It  is  well  known  that  the  addition  of  a  small  amount  of 

PLASTICITY  hydrated  lime  (10%  or  more  by  weight,  of  the  Portland 
OF  CONCRETE  cement  used)  renders  the  concrete  mass  much  more  plastic 
and  that  less  water  is  required  to  make  the  mass  work- 
able. As  the  results  of  experiments  and  practical  observation,  it  has  been 
proven  that  the  small  amount  of  hydrate  improves  greatly  the  ease  of 
handling  the  concrete  and  that  it  further  results  in  a  denser  concrete. 
The  greatest  advantage  of  the  use  of  hydrate  is  this  quality  of  rendering 
the  concrete  mass  more  plastic.  Because  of  this  increased  plasticity  the 
same  amount  of  tamping  results  in  a  denser  concrete. 

An  illustration  of  the  increase  in  plasticity  of  concrete,  due  to  the 
addition  of  hydrated  lime,  recently  came  to  the  author's  observation. 
In  the  construction  of  a  large  dam  in  the  Northwest,  the  quarry  and  rock- 
crushing  plant  were  located  on  a  hillside,  about  400  feet  above  the  river. 
Since  no  good  sand  was  available,  the  fine  part  of  the  aggregate  was 
manufactured  from  the  rock.  The  concrete  mixing  plant  was  also  located 
on  the  hill,  above  the  crest  of  the  dam,  and  practically  all  the  concrete 
was  spouted  into  place  through  chutes  about  285  feet  long,  which  had 
an  inclination  of  18°.  In  this  manner  about  30,000  cu.  yds.  of  concrete 
was  placed.  The  concrete  used  was  a  1:3:5  mix,  using  cement,  sand  and 
stone,  with  an  addition  of  10%  hydrated  lime.  Without  the  addition 
of  the  hydrate,  the  wet  concrete  would  not  flow  in  chutes,  but  would 
dam  up  and  then  spill  over  the  side.  With  the  addition  of  hydrate,  the 
material  flowed  smoothly  and  there  was  very  little  separation  of  the 
mortar  from  the  stone.  Throughout  the  construction  of  the  whole  dam, 
test  cylinders  were  made,  6"  in  diameter  X  12"  long,  and  these  were 
broken  at  regular  intervals.  These  cylinders  were  made  at  the  site  of 
the  dam  from  the  material  being  deposited.  The  result  showed  a  con- 
siderable improvement  both  in  the  quality  and  the  strength  of  the  con- 
crete, due  to  the  hydrated  lime. 

RETENTION  OF  SUFFICIENT  It  is  a  well  known  fact  that  lime  paste  tends 
MOISTURE  TO  PREVENT  to  retain  the  water  mechanically  mixed 

SHRINKAGE  CRACKS  IN  with  it.    This  quality  of  hydrated  lime  is 

CONCRETE  -  particularly  valuable  when  the  concrete  is 

spread  out  in  a  thin  sheet  with  one  surface 

exposed  to  the  air,  as  is  the  case  in  concrete  floors,  sidewalks  and  roads. 
Practical  experience  has  shown  that  the  more  rapidly  the  mass  dries,  the 
greater  the  likelihood  of  cracking.  This  cracking  has  been  attributed  to 
the  fact  that  the  rate  of  surface  evaporation  is  greater  than  the  flow  of 
water  from  the  interior  to  the  surface,  causing  unequal  drying,  a  condi- 
tion which  gives  rise  to  strain  and  more  or  less  marked  ruptures.  During 

66 


CONCRETE  ROAD,  GARRET  Co.,  MARYLAND 

10%  Addition  of  Hydrated  Lime  to  1-2-4  Concrete 

(Monolithic  Type) 

the  early  period  of  drying  out  and  until  the  concrete  has  set  and  hardened, 
it  has  little  or  no  strength,  and  its  cohesion  is  negligible.  In  this  condi- 
tion it  is  evident  that  the  slightest  shrinkage  must  result  in  the  formation 
of  cracks.  Even  though  the  cracks  be  so  small  as  to  be  scarcely  notice- 
able, they  are  a  source  of  weakness  when  the  hardened  concrete  is  subject 
to  tensile  strains.  The  prevention  of  the  formation  of  shrinkage  cracks 
is  not  so  important  in  mass  concrete  subject  only  to  compression  or  in 
reinforced  concrete  where  the  tension  is  provided  for  by  the  steel  rein- 
forcement, but  when  used  in  a  thin  slab  as  is  the  case  in  concrete  roads 
and  pavements,  it  is  very  important  to  reduce  the  cracks  due  to  shrinkage 
to  a  minimum.  The  addition  of  a  small  amount  of  hydrate  to  the  concrete 
mass  reduces  the  formation  of  shrinkage  cracks  by  rendering  the  mass 
denser  and  thereby  retarding  the  evaporation.  Further,  by  rendering  the 
mass  more  plastic,  it  prevents  the  separation  of  the  mortar  from  the  stone, 
thus  producing  a  more  uniform  mass.  In  some  recent  road  work  in 
which  10%  of  hydrated  lime  was  used  throughout  the  concrete,  it  was 
found  that  fewer  cracks  developed  in  this  road  than  in  sections  having 
the  same  composition  but  in  which  no  hydrate  was  used. 


1 1      ** 


BHB 


METHODS  OF          Concrete  can  be  rendered  water-tight   in   a  number 
WATERPROOFING    of  ways: 

CONCRETE  1.     By  carefully  grading  and  proportioning  the  aggre- 

gate and  the  cement. 

2.  By  the  application  of  layers  of  materials  impervious  to  water, 
such  as  asphalts,  bitumen,  etc.,  with  or  without  cloth  or  felt. 

3.  By  plastering  the  outside  surface  of  the  concrete  with  a  rich 
Portland  cement  mortar. 

4.  By  the  introduction  of  some  foreign  material  or  materials  into 
the  mixture. 

Ignoring  the  methods  mentioned  under  Nos.  2  and  3,  which  both 
depend  for  their  water-proofing  quality  upon  a  layer  of  material  impervi- 
ous to  water,  thus  keeping  the  water  away  from  the  concrete  itself,  but 
which  do  not  render  the  concrete  mass  impervious  to  water,  we  will 
deal  only  with  Nos.  1  and  4.  The  greatest  objection  to  the  use  of  imper- 
vious materials  such  as  asphalt,  bitumen,  etc.,  either  with  or  without 
felt  or  cloth,  is  the  durability  of  the  materials  themselves.  In  a  few  years, 
most,  if  not  all,  of  these  substances  oxidize,  disintegrate  and  become 
porous. 

Method  No.  1  depends  on  selecting  materials  which  are  so  graded 
that  they  give  the  densest  possible  concrete.  This  method  is  fully 
described  in  Taylor  and  Thompson's  book  on  "Concrete,  Plain  and 
Reinforced."  The  method  requires  a  careful  selection  of  the  sand  and 
stone,  careful  proportioning  of  the  same,  and  extreme  care  in  mixing 
and  placing. 

NECESSARY  QUALIFICATIONS   It  would  be  a  great  advantage  to  engineers 
FOR  WATERPROOFING  if  some  method  of  rendering  concrete  more 

MATERIAL  -  impervious  to  water  were  known.  Thus,  if 

some  ingredient  could  be  added  to  the  con- 
crete mass  to  produce  this,  the  advantage  would  be  apparent.  Such  an 
ingredient  should  possess  the  following  characteristics: 

1.  It  should  be  easily  mixed  with  the  materials  forming  the  con- 
crete aggregate. 

2.  It  should  not  in  any  way  injure  the  character  of  the  concrete 
or  have  a  deleterious  action  on  the  cement. 

3.  It  should  be  preferably  of  a  character  chemically  similar  to  that 
of  the  cement. 

4.  It    should    not    be    subject   to    alteration,     decomposition    or 
decay,  and  should  be  a  mineral  compound  rather  than  organic. 

70 


5.  The  material  should  be  bulky  and  preferably  of  a  colloidial 
nature,  so  as  to  fill  the  interstices  of  the  concrete  mass. 

6.  It  should  not  be  so  expensive  as  to  make  the  cost  of  the  con- 
crete excessive. 

7.  It  should  be  easily  procurable  and  handled. 

In  looking  over  these  requirements,  it  will  be  seen  that  such  materials 
as  oils,  waxes  and  other  organic  bodies  do  not  fulfill  the  specifications. 
They  are  not  of  a  character  similar  to  the  cement,  are  not  easily  mixed 
with  the  concrete  aggregate,  and,  as  they  are  organic,  are  subject  to 
alteration  and  decay.  Most  of  the  so-called  water-proof  compounds  on 
the  market  at  the  present  time  which  are  to  be  incorporated  in  the  con- 
crete mass  itself  contain  organic  bodies,  such  as  the  lime  salts  of  fatty 
acids,  oils,  paraffin  or  Japanese  wax,  either  alone  or  in  combination  with 
other  ingredients.  While  the  action  of  these  bodies  is  to  render  the  con- 
crete mass  in  the  early  stages  less  impervious  to  water,  it  is  doubtful 
how  long  this  beneficial  action  will  continue. 

In  a  report  of  the  committee  on  water-proofing  rendered  to  the 
American  Society  for  Testing  Materials  and  published  in  the  Proceed- 
ings for  1907,  the  following  statement  is  made: 

"The  only  conclusion  possible  at  the  time,  from  data  so  far  obtained, 
indicates  that  the  majority  of  waterproofing  compounds  examined  under 
the  j  urisdiction  of  sub-committee  A,  are  no  more  effective  than  untreated 
properly  proportioned  mixtures  which  certainly  can  be  made  absolutely 
w^ater-proof  by  the  use  of  proper  materials  and  well  proportioned  mix- 
tures." 

Experiments  made  under  the  author's  direction  confirm  these  con- 
clusions as  applying  to  water-proof  compounds  which  contain  organic 
materials. 


HYDRATED  LIME  AS    Referring  again  to  the  specifications,  it  will  be  seen 

A  WATERPROOFING      that  a  material  to  meet  the  requirements  fully 

MATERIAL  should  have  a  mineral  base  and  should  be  composed 

chiefly  of  lime  so  as  to  be  similar  to  cement  in  its 

chemical  characteristics.  It  would,  therefore,  seem  that  hydrated  lime 
would  be  a  material  which  would  most  nearly  fill  the  requirements.  Clay 
has  been  suggested  as  a  suitable  material,  but  its  use  in  practice  would  be 
impracticable  owing  to  the  tendency  of  its  particles  to  adhere,  forming 
balls;  these  balls  have  little  adhesion,  and  hence  injure  the  strength 
of  concrete. 

71 


RESERVOIR  AT  WALTHAM,  MASSACHUSETTS 
FlVE  PER  CENT.  OF  HYDRATED  LlME  ADDED  BY  WEIGHT  OP  CEMENT 

The  following  results  of  tests  are  given  to  illustrate  the  water- 
proofing properties  of  hydrated  lime: 


TENSILE  STRENGTH  LBS.  PER  SQUARE  INCH* 
1-3  Tests  Water  Exposure 


Age  of 
Test  Piece 

.95  P.  C. 
.05  L. 
3  Sand 

.90  P.  C. 
.10  L. 

3  Sand 

.85  P.  C. 
.15  L. 

3  Sand 

.80  P.  C. 
.20  L. 
3  Sand 

.75  P.  C. 
.25  L. 

3  Sand 

.70  P.  C. 
.30  L. 

3  Sand 

7  days 
28  days 
3  months 
6  months 
9  months 
12  months 

157 
311 
389 
321 
301 
336 

189 
364 
419 
341 
308 
311 

239 
264 
372 
278 
279 
322 

237 

268 
374 
260 
268 
299 

173 
259 
314 
207 
250 
260 

173 

268 
281 
253 
232 
231 

NOTE — P.  C.,  Portland  Cement;    L.,  Hydrated  Lime. 

Percentage  of  Hydrated  Lime  is  by  weight  of  Portland  cement 

These  results  indicate  that  quite  large  additions  of  hydrated  lime 
can  be  made  to  cement  mortars  even  when  they  are  exposed  to  the  action 
of  water.  The  hydrated  lime  in  this  instance  acts  as  a  filling  material, 
and  as  it  is  of  a  colloidial  nature  should  render  the  mortar  more  imper- 
vious to  water. 

In  order  to  investigate  this  water-tight  character  of  mortar,  circular 
pats  were  made  of  the  different  mixtures  3"  in  diameter  and  1"  thick. 
*Lazell — Proceedings  American  Society  for  Testing  Materials,  1908. 

72 


These  were  then  placed  in  an  apparatus  in  such  a  manner  that  the  water 
could  act  upon  them  in  the  centre  through  an  opening  exactly  2"  in 
diameter.  Thus  the  area  acted  upon  is  3.1416  square  inches. 

All  pats  were  subjected  to  a  pressure  of  thirty  pounds  for  one  hour. 


PERMEABILITY  TESTS        1-3  MIXTURES* 


Composition  of 
Test  Piece 

Amount  of  water 

passing  through  test  piece  in  one  hour  under  30  Ib. 
head,  in  cubic  centimeters 

Age  of  Test  Piece 

7  days 

28  days 

Remarks 

IP.  C. 

3  Sand 

10  cc 

0 

.95  P.  C. 
.05  Hydrate 
3  Sand 

5cc 

0 

Equivalent  to  replacing 
5%  of  the  cement  by 
Hydrate 

.90  P.  C. 
.10  Hydrate 
3  Sand 

2cc 

0 

Equivalent  to  replacing 
10%  of  the  cement  by 
Hydrate 

.85  P.  C. 
.  15  Hydrate 
3  Sand 

0.3cc 

0 

Equivalent  to  replacing 
15%  of  the  cement  by 
Hydrate 

NOTE— P.  c  Portland  Cement. 

Percentage  of  lime  is  in  terms  of  weight  of  cement. 

PERMEABILITY  TESTS.     1-5  MIXTURES 


28  days                  6  Weeks                              Remarks 

IP.  C. 

5  Sand 

3000  cc                    1090  cc 

.95  P.  C. 

.05  Hydrate 
5  Sand 

Equivalent  to  replacing 
5  cc                         3  cc          5%  of  the  cement  by 
Hydrate 

.90  P.  C. 

.  10  Hydrate 
5  Sand 

Equivalent  to  replacing 
2  .  5  cc                          0               10%  of  the  cement  by 
Hydrate 

.85  P.  C. 
.  15  Hydrate 
5  Sand 

Equivalent  to  replacing 
0                                0               15%  of  the  cement  by 
Hydrate 

NOTE— P.  C.,  Portland  Cement. 
Percentage  of  lime  is  in  terms  of  weight  of  cement. 

*E.  W.  Lazell — Proceedings  American  Society  for  Testing  Materials,   1908. 

73 


Referring  to  the  preceding  tests  it  will  be  seen  that  the  addition  of 
even  small  amounts  of  hydrated  lime  to  mortar  materially  increases  its 
water-tightness. 

Sanford  E.  Thompson,*  in  an  address  delivered  before  the 
American  Society  for  Testing  Materials,  in  June,  1908,  gave  tests  upon 
the  concrete  used  for  the  Waltham,  Mass.,  reservoir  as  follows: 

"A  few  permeability  tests  with  hydrated  lime  admixtures  made  by 
the  writer  in  1903  indicated  it  to  be  a  valuable  material  for  water-proof- 
ing. Later  in  1906  when  the  reservoir  at  Waltham,  Mass.,**  which  is 
100  feet  in  diameter  and  43  feet  high,  was  under  consideration,  the  writer 
was  consulted  by  Bertram  Brewer,  City  Engineer,  in  the  framing  of 
the  specifications  and  made  another  series  of  tests  as  follows: 


Permeability  Test  of  1:2:4  Concrete  for  Waltham,  Mass.,  Reservoir,  1906 
Concrete  4  in.  thick.  Pressure  80  Ibs.  per  sq.  in. 


Percentage  of 
Hydrated  Lime 

Flow  in  Grams  per  minute 

At  14  days 

At  21  days 

At  28  days 

0% 

A 

5.52 
9.20 

2.82 

2.92 
2.55 
1.49 

1.91 
1.63 
0.76 

Percentage  of  lime  is  in  terms  of  weight  of  cement. 

"This  flow  is  much  greater  than  in  the  tests  described  at  Cambridge, 
but  the  pressure  in  the  Cambridge  tests  is  about  one- third  higher,  the 
age  is  greater,  and  probably,  most  important  of  all,  the  thickness  of 
concrete  is  twice  as  great. 

"As  a  result  of  those  tests  for  Waltham,  5%  of  hydrated  lime  was 
adopted  for  the  reservoir  to  mix  with  the  1 :2 :4  concrete  in  building  its 
walls.  The  results  were  satisfactory,  the  only  seepage  occurring  at 
joints  formed  between  different  day's  work,  where  the  bond  between 
the  old  and  the  new  concrete  was  not  made  with  sufficient  care.'* 

fin  a  recent  address  by  Sanford  E.  Thompson,  given  before  the 
American  Society  for  Testing  Materials,  in  June,  1908,  he  discussed  a 
series  of  tests  made  on  concrete  composed  of  Portland  cement,  sand  and 
stone  in  varying  proportions  to  which  had  been  added  varying  amounts 
of  hydrated  lime.  In  making  these  tests,  concrete  cubes  were  used  con- 
taining an  embedded  pipe  through  which  the  water  pressure  could  be 
applied.  The  results  are  given  in  the  table  on  following  page: 
*Engineering  Record  June  27,  1908. 

**Engineering  Record  January  12,  1907,  Page  32. 
tEngineering  Record  June  27,  1908. 


74 


Flow  of  water 
under  7-ft.  head 


Flow  under  pressure 
of  60  Ibs.  per  sq.  in. 


Pressure 

Per  cent. 

Duration 

Flow 

applied 

Duration 

Flow 

Mark 

Hydrat- 
ed  Lime 

Age 

of   meas- 
ured flow 

Grams 
Hour 

Age 

before 
measure 

of   meas- 
ured flow 

Grams 
per 
Hour 

Days 

Hours 

Days 

Hours 

Hours 

1:2:4  concrete 

No.l 

1% 

18 

161 

2.7 

40 

24 

4M 

74.8 

No.  2 

4% 

18 

161 

1.2 

41 

18 

5 

28.4 

No.  3 

7% 

18 

161 

1.0 

42 

18 

G% 

5.2 

No.  4 

10% 

15 

161 

1.0 

46 

6 

18 

1.6 

1:2^:4^  con. 

No.  5 

0% 

30 

169 

0.3 

44 

17 

6 

1.1 

No.  6 

o% 

30 

169 

1.9 

45 

18 

6 

32.5 

No.  7 

10% 

29 

169 

0.8 

49 

11 

0 

No.  8 

14% 

29 

169 

0.7 

50 

27 

0 

1:3:5  concrete 

No.    9 

o% 

26 

169 

9.8 

50 

6 

14 

70.6 

No.  10 

8% 

26 

169 

1.1 

51 

8 

17 

3.6 

No.  11 

14% 

28 

169 

1.1 

50 

28 

13 

10.7 

No.  12 

20% 

28 

169 

1.2 

53 

9 

15 

0.7 

"The  percentages  of  hydrated  lime  are  based  on  the  weight  of  the 
cement,  these  being  added  to  the  cement  and  not  replacing  it.  The 
variations  in  the  ages  of  the  specimens  in  different  proportions  slightly 
affects  the  results  and  accounts  in  part  for  the  fact  that  the  1 :3 :5  mix- 
tures in  the  pressure  tests  are  nearly  as  water-tight  as  the  richer  propor- 
tions. Specimen  No.  5,  which  shows  practically  no  flow,  is  evidently 
erratic." 

He  concludes  from  these  experiments  as  follows: 

"  (1)     Hydrated  lime  increases  the  water- tight  ness  of  concrete. 

"(2)  Effective  proportions  of  hydrated  lime  for  water-tight  con- 
crete are  as  follows: 

"For  one  part  Portland  cement:  2  parts  sand:  4  parts  stone,  add 
8  per  cent  hydrated  lime. 

"For  1  part  Portland  cement:  2J/^  parts  sand:  4 3^  parts  stone,  add 
12  per  cent  hydrated  lime. 

"For  1  part  Portland  cement:  3  parts  sand:  5  parts  stone,  add  16 
per  cent  hydrated  lime. 

"These  percentages  are  based  on  the  weight  of  the  dry  hydrated 
lime  to  the  weight  of  the  dry  Portland  cement. 

"  (3)  The  cost  of  large  waterproof  concrete  structures  frequently 
may  be  reduced  by  employing  leaner  proportions  of  concrete  with  hy- 
drated lime  admixtures,  and  small  structures,  such  as  tanks,  may  be 
made  more  water-tight. 

"  (4)  Lime  paste  made  from  a  given  weight  of  hydrated  lime  oc- 
cupies about  2  J4  times  the  bulk  of  paste  made  from  the  same  weight  of 
Portland  cement,  and  is  therefore  very  efficient  in  void  filling. 


75 


5      "i 


<    e- 

\  I 

I   I 


£  1 

a  3 

H 

03  tJ 

g  5 

§  2 

S  ^3 

^  E& 


"Although  the  character  of  the  sand  and  stone  used  in  the  concrete 
will  affect  the  best  percentage  of  lime  to  use,  the  present  materials  are 
representative  of  average  materials  throughout  the  country  so  that  the 
results  should  be  of  general  application.  Coarser  sand  would  naturally 
require  slightly  larger  percentages  of  lime  and  finer  sand,  that  is,  sands 
having  a  larger  percentage  of  fine  grains,  which  pass  a  sieve  with  40 
meshes  to  the  linear  inch,  would  be  apt  to  require  less  lime  since  sands 
containing  considerable  fine  material  produce  a  more  water-tight  al- 
though a  weaker  concrete." 

In  these  experiments  of  Thompson  a  water  pressure  of  60  pounds  to 
the  square  inch  was  used,  which  is  equivalent  to  a  head  of  about  140 
feet.  This  is  more  severe  than  is  encountered  in  the  general  engineering 
practice. 

The  conclusions  to  be  drawn  from  the  investigations  given  indicate 
that  in  hydrated  lime  we  have  the  best  material  at  present  known  for 
rendering  concrete  water-tight.  Hydrated  lime,] however,  must  not  be 
confounded  with  quick-lime,  which  is  absolutely  unfit  to  be  used  in 
concrete.  The  effect  of  the  addition  of  hydrated  lime  in  small  quantities 
is  mostly  mechanical,  filling  the  voids,  thus  making  the  concrete  imper- 
vious to  water.  The  quantity  which  should  be  used  depends  upon  the 
fineness  of  the  sand  employed  and  the  proportions  of  the  mixture.  The 
concrete  materials  must  be  properly  graded,  the  proper  proportions  of 
cement  and  hydrated  lime  used.  Even  with  this  preliminary  care,  if 
the  concrete  is  poorly  mixed  with  insufficient  water,  or  improperly 
placed,  or  if  joints  are  left,  the  walls  will  inevitably  leak.  The  mixing 
must  be  thorough;  sufficient  water  must  be  employed  to  give  a  "  mushy  '* 
mixture  so  that  it  will  settle  into  place  with  the  least  amount  of  ramming. 
Fully  as  important  as  the  care  in  mixing  is  the  bonding  of  one  day's 
concrete  with  the  next;  even  small  interruptions  of  an  hour  on  a  hot  day 
will  materially  injure  the  bond  of  the  concrete.  It  is,  therefore,  necessary 
that  if  water-tight  work  is  to  be  done,  the  greatest  care  should  be  exer- 
cised both  in  the  selection  of  the  materials,  proportions  of  the  ingredients, 
mixing  and  placing  the  same.  Hydrated  lime  can  be  advantageously  used 
only  in  mixtures  as  lean  or  leaner  than  1-2-4  unless  the  hydrated  lime 
is  substituted  for  an  equal  weight  of  cement.  Ten  per  cent  by  weight 
of  the  cement  has  been  found  a  convenient  amount  in  a  number  of 
instances.  Hydrated  lime  is  a  bulky  material,  the  same  weight  oc- 
cupying about  two  and  one-half  times  the  volume  of  the  same  weight 
of  cement. 


77 


HOTEL  OREGON,  PORTLAND,  OREGON 

DOTLE-l'ATTERSON,  ARCHITECTS 
Hydrated  Lime  Used  in  Concrete  and  Brick  Mortar 


ADVANTAGES  OF  HYDRATED  LIME 
OVER  OTHER  FORMS  OF  LIME. 

CHAPTER  X 

HYDRATED  lime  is  generally  purer  than  the  quick  lime  from  which 
I  it  is  made.    Chapter  VIII,  Page  50. 

Hydrated  lime  is  easily  subjected  to  inspection  and  tests,  and  the 
same  material  is  tested  as  is  used.    Chapter  VIII,  Page  50. 

The  use  of  hydrated  lime  does  away  with  the  slaking  of  lump 
lime,  hence  saves  the  cost  and  the  space  required  for  this  operation. 
Chapter  VIII,  Page  50. 

Hydrated  lime  is  thoroughly  slaked  and  this  fact  can  be  deter- 
mined by  tests.  Chapter  VIII,  Page  50. 

By  the  use  of  hydrated  lime  mortar  definite  proportions  can  be 
maintained.  This  is  a  difficult  matter  with  lump  lime.  Chapter  VIII, 
Page  49.  Table  Page  53. 

The  putty  or  mortar  made  wTith  hydrated  lime  requires  no  aging 
to  be  assured  of  thorough  slaking.  The  Romans  recognized  the  neces- 
sity of  long  aging  for  lime  paste  and  an  old  Roman  law  required  that 
lime  be  slaked  three  years  before  using.  In  the  south  of  Europe  at  the 
present  time  it  is  the  custom  to  slake  lime  the  season  before  it  is  used. 
Chapter  V,  Page  38. 

Hydrated  lime  can  be  economically  mixed  by  means  of  a  mortar 
mixer.  Chapter  VIII,  Page  52. 

Mortars  made  from  hydrated  lime  are  stronger  than  mortars  made 
from  lump  lime  slaked  to  a  paste.  Chapter  VIII,  Pages  57  to  60. 

Hydrated  lime  can  be  mixed  with  cement  mortar  or  concrete  in  any 
desired  proportions.  It  is  a  very  difficult  matter  to  mix  lime  paste 
with  cement  thoroughly.  Chapter  VIII,  Page  56. 

Hydrated  lime  can  be  stored  without  danger  of  fire.  No  heat  is 
generated  when  water  comes  in  contact  with  hydrate. 

Hydrated  lime  is  not  apt  to  be  spoiled  by  air  slaking,  as  is  the 
case  with  lump  lime.  Often  large  amounts  of  lime  are  lost  in  this  manner. 

Hydrated  lime  comes  into  the  market  in  packages  of  definite  weight 
and  convenient  size. 

79 


The  paper  sacks  generally  used  cost  less  than  half  as  much  as  the 
barrels  required  to  hold  an  equal  weight  of  lump  lime. 

The  paste  made  from  hydrated  lime  requires  no  screening. 

There  is  no  loss  in  the  form  of  "core"  when  hydrated  lime  is  used. 

Against  all  these  advantages  only  two  objections  are  obvious.  One, 
the  mortar  made  from  hydrated  lime  often  works  harder  and  is  less 
plastic  than  that  made  from  lump  lime.  This  difficulty  is  generally 
greatly  exaggerated.  Second,  hydrated  lime  will  not  carry  so  much  sand 
as  a  corresponding  weight  of  lump  lime.  This  fact  has  been  explained 
on  page  52. 

The  second  objection  is  dependable  upon  the  first,  because  the  larger 
sand  carrying  capacity  of  lump  lime  paste  is  due  to  its  plasticity,  or 
buttery,  easy  working  quality.  This  quality  of  lump  lime  usually  results 
in  the  addition  of  too  much  sand.  The  oversanding  of  lime  mortar  is 
very  generally  practiced,  since  it  is  the  custom  to  add  as  much  sand  as 
possible  in  order  to  cheapen  the  cost  of  the  mortar.  This  results  in  a 
lean,  oversanded  mortar  possessing  little  strength.  The  manufacturers 
of  lime  are  not  blameless  in  this  respect,  since  they  have  educated  the 
public  to  believe  that  the  greater  the  yield  of  paste  from  a  barrel  of 
lime  the  more  sand  it  will  carry,  overlooking  the  fact  that  a  leaner  lime, 
or  one  which  does  not  yield  as  great  a  volume  of  paste,  produces  a  much 
stronger  mortar. 

The  increase  in  bulk  when  lime  is  slaked  is  mostly  due  to  the  water 
mechanically  absorbed.  When  the  lime  mortar  hardens,  this  water 
evaporates,  causing  it  to  shrink  and  the  excess  water  is  therefore  a  source 
of  weakness  and  not  strength.  The  greater  the  amount  of  water  held 
mechanically,  the  greater  the  volume  of  the  paste,  and  therefore  the  less 
the  amount  of  binding  ingredient  or  lime  contained  in  a  volume  of  paste. 
This  point  is  brought  out  clearly  from  the  table  on  page  35. 

It  has  been  proven  by  many  experiments  that  the  poorer  limes  make 
the  stronger  mortars.  These  poor,  or  lean  limes  contain  clay,  which 
unites  with  the  lime  during  the  process  of  burning,  and  the  presence  of 
this  clay  imparts  some  hydraulic  or  hardening  properties  to  the  mortar. 
These  hydraulic  limes  are  largely  used  in  Europe,  but,  unfortunately, 
little  of  this  material  has  been  manufactured  in  this  country.  Practically 
the  same  results  can  be  obtained  by  the  use  of  a  mixture  of  hydrated 
lime  and  Portland  cement. 

From  all  the  advantages  possessed  by  hydrated  lime  it  would  appear 
to  be  the  best  form  of  lime  to  be  used.  It  is  perfectly  logical  that  the 
process  of  slaking  should  be  taken  away  from  the  haphazard  manner 
used  on  the  work  and  done  at  the  point  of  manufacture  of  the  lime  where 
skillful  supervision  is  possible. 

80 


APPENDIX  I. 

Useful  Data — Lime. 

DEFINITION — Lime  is  the  product  resulting  from  calcining  (burning)  of 

limestone,  which  slakes  upon  the  addition  of  water. 
WEIGHT — Lump  lime  weighs  from  50  to  60  pounds  per  cubic  foot. 
BARREL — A  200  pound  barrel  of    lime    contains    185  pounds    net   of 

lump  lime,  or  3.1  cubic  feet. 

A  300  pound  barrel  of  lime  contains  280  pounds  net  of  lime  or  4.7 

cubic  feet. 
BUSHEL — A  bushel  of  lime  is  from  75   to  80  pounds,   depending  upon 

the  law  in  the  state  in  which  the  lime  is  purchased. 

A  bushel  contains  from  1  to  1.3  cubic  feet. 
PASTE — Lime  paste  is  a  mixture  of  slaked  lime  and  water. 
SLAKING — A    pound   of    high   calcium   lime   requires    from    1    to    1J^ 

pounds  of  water  to  form  a  paste. 

A  pound  of  dolomitic  lime  requires  about  1  pound  of  water  to  form 

a  paste. 

A  barrel  of  high  calcium  lime  requires  from  30  to  40  gallons  of  water 

to  produce  a  paste. 

A  barrel  of  dolomitic  lime  requires  from  25  to  30  gallons  of  water 

to  produce  a  paste. 

SLAKING — Slaking  is  the  most  important  operation  in  preparing  mortar. 
BURNING — Lime  must  not  be  burned  in  slaking. 

Burning  results  from  the  use  of  too  little  water  or  insufficient  mixing 

during  slaking. 
DROWNING — Lime  must  not  be  drowned  in  slaking. 

Drowning  results  from  the  use  of  too  much  water. 
AGING — Lime  used  for  plastering   should   be    slaked   at  least  3  weeks 

before  using.     The  longer  the  paste  is  aged  the  better  the  quality 

of  the  mortar. 
VOLUME  OF  PASTE — A  barrel  of  lime    gives   from  6    to  9    cubic    feet 

of  paste;    average  about  7^  cubic  feet. 

Hydrated  Lime. 

DEFINITION — Hydrated  lime  is   a   dry,   specially  prepared  slaked  lime. 
WEIGHT — Hydrated  lime  weighs  from  36    to    45    pounds    per    cubic 
foot;    average  about  40  pounds. 

81 


SACK — A  100  pound  sack  of  hydrated  lime   contains    about    2J/2   cu- 
bic feet. 

PASTE — It  requires  about  an  equal  weight  of  water  to  produce  a  paste. 
A  100  pound  sack  of  hydrate  gives  about  2.3  cubic  feet  of  paste  of 
ordinary  consistency. 

Portland  Cement. 

DEFINITION — Portland  cement  is  made    from  a   mixture   of    materials 

containing  lime  and  clay. 

WEIGHT — A  barrel  of  Portland   cement   weighs  376   pounds   net,   and 
contains  3.8  cubic  feet. 

A  bag  of  Portland  cement  weighs  94  pounds  and  contains  about 

1  cubic  foot. 
PACKED — Packed  cement  weighs  on  the    average    115    pounds  to  the 

cubic  foot. 
LOOSE — Loose  Portland  cement  weighs  on  the  average  92  pounds  to 

the  cubic  foot. 
CUSTOMARY  WEIGHT — In  general    a  sack   of  cement  is    considered  to 

be  1  cubic  foot  and  to  weigh  100  pounds. 
PASTE — Cement  paste  is  a  mixture  of  cement  and  water. 
WEIGHT  OF  PASTE — Cement    paste    weighs    about    137     pounds    to 

the  cubic  foot. 

Sand. 

QUALITY — The  quality  of  sand  is  chiefly  dependent  upon  the  coarseness 

and  the  relative  size  of  the  grains. 
CLAY  OB  LOAM — Clay  or  loam  in  sand   is   often  injurious  to   mortar 

because  too  much  fine  material  is  introduced. 
SPECIFIC  GRAVITY — Specific  gravity  of  sand  is  about  2.65. 
WEIGHT — Sand  weighs  from  80  to  120    pounds    to    the    cubic    foot, 

average  about  100  pounds. 
COARSE  SAND — Coarse   sand   requires    less  water  than  fine    sand    and 

gives  a  stronger  mortar. 
MIXED  SAND — Mixed  sands  usually  weigh  more   and  contain  a  smaller 

volume  of  voids  than  coarse  or  small  sands. 
FINE  SAND — Fine  sand  with  grains  of  uniform  size  weighs   nearly  the 

same  when  dry  and  has  nearly  the  same  percentage  of  voids  as 

screened  sand.     Fine  sand  with  ordinary  moisture  is  lighter  and 

more  porous  than  coarse  sand. 
VOIDS — Voids  are  the  spaces  in  a  mass  of  sand    or  mortar    that    are 

filled  with  water  or  air. 

82 


VEGETABLE  MATTER — Even  a  small  amount  of  vegetable  matter 
present  in  sand  may  result  in  a  weak  mortar. 

Mortar. 

DEFINITION — Mortar  is  a  mixture  of  sand  and  water  with  some  binding 
material,  such  as  lime,  cement,  or  both. 

STRONGEST  MORTAR — Is  obtained  from  those  sands  which  produce  the 
smallest  volume  of  plastic  mortar. 

FINE  SANDS — Always  produce  a  mortar  of  less  strength  than  coarse 
sands. 

MIXTURES  OF  FINE  AND  COARSE  SANDS — Often  produce  a  stronger 
mortar  than  either  material  alone. 

CLAY  OR  LOAM — In  sand  generally  weakens  a  rich  mortar  and  may 
strengthen  a  lean  mortar. 

WEIGHT — The  weight  of  lime  or  cement  mortar  varies  with  the 
proportions  as  well  as  with  the  materials  of  which  it  is  composed. 
Average  weight  of  lime  mortar  is  about  120  pounds  per  cubic  foot. 
Average  weight  of  1-3  cement  mortar  is  135  pounds  per  cubic  foot. 

PROPORTIONS — Proportions  must  be  accurately  measured. 

MIXING — Mixing  must  be  thorough.  All  mortars  are  improved  by 
long  mixing. 

MACHINE  MIXING — Machine  mixing  is  better  than  hand  mixing  and 
gives  more  plastic  mortar. 

Quantities. 

AVERAGE  WOODEN  WHEELBARROW  LOAD  of  broken  stone  is  about  2.4 

cubic  feet. 

AVERAGE  WOODEN  WHEELBARROW  LOAD  of  sand  is  about  2J/2  cubic  feet. 
AVERAGE  IRON  WHEELBARROW  LOAD  of  stone  or  gravel  is  about  3  cubic 

feet. 
AVERAGE  IRON  WHEELBARROW  LOAD  of  sand  is  about  3j/£  cubic  feet. 

SHOVEL — A  No.  2  shovel  holds  about  15  pounds  of  sand. 
A  No.  3  shovel  holds  about  18  pounds  of  sand. 
A  No.  4  shovel  holds  about  20  pounds  of  sand. 

BUCKET — A  3  gallon  (12  quart)  bucket  holds  16  pounds  of  hydrata. 
A  3  gallon  (12  quart)  bucket  holds  35  pounds  of  sand. 
A  3  gallon  (12  quart)  bucket  holds  40  pounds  of  cement. 

88 


APPENDIX   II. 

Standard  Specifications  for  Hydrated  Lime* 

SERIAL  DESIGNATION:   C6-15. 

The  specifications  for  this  material  are  issued  under  the  fixed  designa- 
tion C6;  the  final  number  indicates  the  year  of  original  issue,  or  in  the 
case  of  revision,  the  year  of  last  revision. 

ADOPTED,  1915. 

1.  DEFINITION. — Hydrated  lime  is  a  dry  flocculent  powder  resulting 

from  the  hydration  of  quicklime, 

2.  CLASSES. — Hydrated  lime  is  commercially  divided  into  four  classes: 

(a)  — High- Calcium ; 
(b) — Calcium; 
(c)  — Magnesian ; 
(d) — High-Magnesian. 

3.  BASIS  OF  PURCHASE. — The  particular  class  of  hydrated  lime  desired 

shall  be  specified  in  advance  by  the  purchaser. 

I.     CHEMICAL  PROPERTIES  AND  TESTS. 

4.  SAMPLING. — The  sample  shall  be  a  fair  average  of  the  shipment. 

Three  per  cent  of  the  packages  shall  be  sampled.  The  sample 
shall  be  taken  from  the  surface  to  the  center  of  the  package.  A 
2-lb.  sample  to  be  sent  to  the  laboratory  shall  immediately  be 
transferred  to  an  air-tight  container,  in  which  the  unused  portion 
shall  be  stored  until  the  hydrated  lime  has  been  finally  accepted 
or  rejected  by  the  purchaser. 

5.  CHEMICAL  PROPERTIES. — (a) — The  classes  and  chemical  properties 

of  hydrated  lime  shall  be  determined  by  standard  methods  of 
chemical  analysis. 

(b) — The  non- volatile  portion  of   hydrated  lime  shall  conform   to 
the  following  requirements  as  to  chemical  composition: 
'Authorized  reprint  from  the  copyrighted  Year  Book  for  1915  of  the  American  So- 
ciety for  Testing  Materials,  Philadelphia,  Pa. ,  U.  S.  A. 

84 


CHEMICAL  COMPOSITION 


Properties  Considered. 

High- 
Calcium 

Calcium 

Magnesian 

High- 
Magnesian 

Calcium  Oxide  per  cent 

90  (min.) 

85-90 

Magnesium  Oxide  per  cent.  . 

10-25 

25  (min  ) 

Silica  plus  Alumina  plus  Oxide  of 

Iron  max    per  cent.  . 

5 

5 

5 

5 

Carbon  Dioxide,  max.,  per  cent  

5 

5 

5 

5 

\Vater                  

Sufficient  to 

Sufficient  to 

Sufficient  to 

Sufficient  to 

hydrate  the 

hydrate  the 

hydrate  the 

hydrate  the 

calcium- 

calcium- 

calcium- 

calcium- 

oxide 

oxide 

oxide 

oxide 

content 

content 

content 

content 

II.     PHYSICAL  PROPERTIES  AND  TESTS. 

6.  FINENESS. — A  100-g.  sample  shall  leave  by  weight  a  residue  of  not 

over  5  per  cent  on  a   standard  100-mesh  sieve  and  not  over  0.5 
per  cent  on  a  standard  30-mesh  sieve. 

7.  CONSTANCY  OF  VOLUME. — Hydrated  lime  shall  be  tested  to  deter- 

mine its  constancy  of  volume  in  the  following  manner: 

Equal  parts  of  hydrated  lime  under  test  and  volume-constant 
Portland  cement  shall  be  thoroughly  mixed  together  and  gauged 
with  water  to  a  paste.  Only  sufficient  water  shall  be  used  to  make 
the  mixture  workable.  From  this  paste  a  pat  about  3  in.  in  dia- 
meter and  J/-2  in.  thick  at  the  center,  tapering  to  a  thin  edge  shall  be 
made  on  a  clean  glass  plate  about  4  in.  square.  This  pat  shall  be 
allowed  to  harden  24  hours  in  moist  air  and  shall  be  without  pop- 
ping, checking,  cracking,  warping  or  disintegration  after  5  hours* 
exposure  to  steam  above  boiling  water  in  a  loosely  closed  vessel. 

III.    PACKING  AND  MARKING. 

8 .  PACKING. — Hydrated  lime  shall  be  packed  either  in  cloth  or  in  paper 

bags  and  the  weight  shall  be  plainly  marked  on  each  package. 

9.  MARKING. — The  name  of  the  manufacturer  shall  be  legibly  marked 

or  tagged  on  each  package. 

IV.     INSPECTION  AND  REJECTION. 

10.  INSPECTION. — (a) — All  hydrated  lime  shall  be  subject  to  inspection. 

(b) — The  hydrated  lime  may  be  inspected  either  at  the  place 
of  manufacture  or  the  point  of  delivery,  as  arranged  at  the  time  of 
purchase. 


85 


(c) — The  inspector  representing  the  purchaser  shall  have  free 
entry  at  all  times  while  work  on  the  contract  of  the  purchaser  is 
being  performed,  to  all  parts  of  the  manufacturer's  works  which 
concern  the  manufacture  of  the  hydrated  lime  ordered.  The  manu- 
facturer shall  afford  the  inspector  all  reasonable  facilities  for  inspec- 
tion and  sampling,  which  shall  be  so  conducted  as  not  to  interfere 
unnecessarily  with  the  operation  of  the  works. 

(d) — The  purchaser  may  make  the  tests  to  govern  the  acceptance 
or  rejection  of  the  hydrated  lime  in  his  own  laboratory  or  elsewhere. 
Such  tests,  however,  shall  be  made  at  the  expense  of  the  purchaser. 

11.  REJECTION. — Unless  otherwise   specified,   any  rejection  based  on 
failure  to  pass  tests  prescribed  in  these  specifications  shall  be  re- 
ported within  five  working  days  from  the  taking  of  samples. 

12.  REHEARING. — Samples  which  represent  rejected  hydrated  lime  shall 
be  preserved  in  air-tight  containers  for  five  days  from  the  date  of 
the  test  report.     In  case  of  dissatisfaction  with  the  results  of  the 
tests,  the  manufacturer  may  make  claim  for  a  rehearing  within 
that  time. 


APPENDIX  III. 


QUANTITIES  OF  MATERIALS  FOR  ONE  CUBIC  YARD  OF  PLASTIC  MORTAR 
HYDRATED  LIME  MORTAR 

One  bag  of  hydrate  equals  100  pounds,  2^  cubic  feet 

TABLE  No.   1 
PARTS  BY  VOLUME 


Proportions 
Parts 

Proportions 
By 
Volume 

Volume  of 
Mortar  from 
One  Bag 

Quantities  of  Materials  to 
Make  1  Cubic  Yard 
of  Mortar 

Hydrate 

Sand 

Hydrate 
Bags 

Sand 
Cu.  Ft. 

Cu.  Ft. 

Hydrate 
Bags 

Sand 
Cu.  Yds. 

1 

2.50 

3.44 

7.84 

0.73 

IX 

2 

3.75 
5.00 

4.61 
5.79 

5.85 
4.66 

0.81 
0.86 

2j^ 

6.25 

6.97 

3.87 

0.89 

3 

7.50 

8.15 

3.31 

0.92 

3% 

8.75 

9.32 

2.90 

0.94 

4 

10.00 

10.50 

2.57 

0.95 

43^ 

11.25 

11.67 

2.31 

0.96 

5 

1 

12.50 

12.85 

2.10 

0.97 

NOTES — Variations  in  the  fineness  of  the  sand  and  in  the  consistency  of  the  mortar 
may  affect  the  yield  of  mortar  by  10%  in  either  direction. 

Hydrated  Lime  requires  about  its  own  weight  of  water  to  be  reduced  to  a  paste.  The 
volume  of  this  paste  is  about  90%  of  the  volume  of  dry  hydrate. 

The  volume  of  mortar  refers  to  its  volume  in  a  plastic  condition  as  mixed,  not  to  its 
volume  after  ramming  or  hardening. 


TABLE  No.   1-A 
PARTS  BY  WEIGHT 


Proportions 
By 

Parts 

Proportions 
By 
Volume 

Volume  of 
Mortar  from 
One  Bag 

Quantities  of  Materials  to 
Make  1  Cubic  Yard 
of  Mortar 

Hydrate 

Sand 

Hydrate 

Bags 

Sand 
Cu.  Ft. 

Cu.  Ft. 

Hydrate 
Bags 

Sand 
Cu.  Yds. 

1 
1 
1 
1 
1 
1 
1 
1 
1 

1 

IX 

2 

&A 
3 

&A 

VA 

5 

1 

IX 

2 

VA 

3 

3^ 
4 
4^ 
5 

2.00 
2.46 
2.94 
3.44 
3.89 
4.37 
4.83 
5.31 
5.79 

13.50 
10.96 
9.19 
7.84 
6.93 
6.17 
5.59 
5.08 
4.66 

0.50 
0.61 
0.68 
0.73 
0.77 
0.80 
0.83 
0.85 
0.86 

87 


QUANTITIES  OF  MATERIALS  FOR  ONE  CUBIC  YARD  OF  PLASTIC  MORTAR. 
HYDRATED  LIME  MORTAR  WITH  ADDITION  OF  PORTLAND  CEMENT. 

TABLE  No.   2 
PARTS  BY  VOLUME 


Proportions 

Proportions 

Pounds  of  Portland  Cement 

by 

For  One  Cubic  Yard 

Required  for  Each  Per  Cent.  Added 

Parts 

by  Volume 

Hydrate 

Sand 

5% 

10% 

15% 

20% 

25% 

Hydrate 

Sand 

Bags 

Cu.  Yds. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

2 

4.66 

0.86 

23 

46 

70 

92 

115 

2j^ 

3.87 

0.89 

19 

39 

58 

78 

97 

3 

3.31 

0.92 

16 

32 

48 

64 

83 

3/^2 

2.90 

0.94 

15 

29 

43 

58 

72 

4 

2.57 

0.95 

14 

27 

40 

51 

64 

1 

4/^ 

2.31 

0.96 

12 

23 

35 

46 

58 

1 

5 

2.10 

0.97 

11 

22 

33 

44 

54 

NOTES — Variations  in  the  fineness  of  the  sand  and  in  the  consistency  of  the  mortar  may 
affect  the  yield  of  mortar  by  10%  in  either  direction. 

The  amount  of  Portland  cement  added  is  a  percent  of  the  amount  of  Hydrate  used. 
A  cubic  foot  of  dry  hydrate  weighs  40  Ibs. 
A  cubic  foot  of  Portland  cement  weighs  100  Ibs. 


TABLE  No.  2-A 

PARTS  BY  WEIGHT 


Proportions 

by 
Parts 

Proportions 
For  One  Cubic  Yard 
by  Volume 

Pounds  of  Portland  Cement 
Required  for  Each  Per  Cent.  Added 

Hydrate 

Sand 

Hydrate 
Bags 

Sand 
Cu.  Yds. 

5% 
Lbs. 

10% 
Lbs. 

15% 
Lbs. 

20% 
Lbs. 

25% 
Lbs. 

1 
1 
1 
1 
1 
1 
1 

2 

V/2 
3 

3K 

4^ 
5 

9.19 
7.84 
6.93 
6.17 
5.59 
5.08 
4.66 

.68 
.73 

.77 
.80 
.83 
.85 
.86 

46 
39 
35 
31 

28 
25 
23 

92 
78 
69 
62 
56 
51 
47 

138 
118 
104 
93 
84 
76 
70 

184 
157 
139 
123 
111 
102 
93 

230 
196 
173 
154 
140 
127 
116 

88 


QUANTITIES  OF  MATERIALS  FOR  ONE  CUBIC  YARD  OF  PLASTIC  MORTAR. 

CEMENT  MORTAR  WITH  HYDRATED  LIME  ADDITIONS. 

TABLE  No.   3 


Volume 

Proportions  by 
Parts,    Weight 

Proportions 
by 

Re- 
sulting 

Quantities  to 
Make  1  Cubic 

Pounds  of  Hydrate 
Required  for  Each  Percent 

or  Volume 

Volume 

Mortar 

Yard  of 

Added 

Cu.   Ft. 

Mortar 

From 

C  ement 

Sand 

Cement 

Sand 

1  Bbl. 

Cement 

Sand 

5% 

10% 

15% 

20% 

25% 

Bbls. 

Cu.  Ft. 

Cement 

Bbls. 

Cu.  Yd. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

Lbs. 

1 

2 

1 

7.6 

10.0 

2.70 

.76 

50 

101 

151 

202 

252 

1 

2^ 

1 

9.5 

11.8 

2.29 

.81 

43 

86 

129 

172 

215 

1 

3 

1 

11.4 

13.7 

.97 

.83 

38 

74 

111 

148 

186 

1 

SH 

1 

13.3 

15.5 

1.74 

.86 

32 

65 

97 

130 

162 

1 

4 

1 

15.2 

17.3 

1.56 

.88 

29 

58 

87 

116 

145 

1 

4^ 

1 

17.1 

19.1 

1.41 

.89 

26 

53 

79 

106 

132 

1 

5 

1 

19.0 

21.0 

1.28 

.90 

24 

48 

72 

96 

120 

NOTE — Variations  in  the  fineness  of  the  sand  and  in  the  consistency  of  the  mortar  may 
affect  the  yield  of  mortar  by  10%  in  either  direction. 

The  amount  of  Hydrated  Lime  is  a  percent  of  the  amount  of  Portland  cement  used. 


QUANTITIES  OF  MATERIALS  FOR  ONE  CUBIC  YARD  OF  PLASTIC  MORTARS 
HYDRATED  LIME-PORTLAND  CEMENT  MORTAR 

Equal  Parts  of  Hydrate  and  Cement 

TABLE  No.   4 
PARTS  BY  VOLUME 


Proportions 

Volume  of 

Quantities  of  Materials 

by 

Proportions  by 

Mortar  from 

to  Make  1  Cubic  Yard 

Parts 

Volume 

1-40  Ib.  Bag 

TT    -J_~J-^     OM/J      1 

Hydrate 

Cement 

100  Ib.  Bag 

Hydrate 

Cement 

Sand 

Hy- 

Ce- 

40 Lbs. 

100  Lbs. 

Sand 

Cement 

40  Ib. 

100  Ib. 

Cu.  Yd. 

drate 

ment 

Sand 

Bag 

Bag 

Cu.  Ft. 

Cu.  Ft. 

Bag 

Bag 

1 

1 

3 

3 

4.18 

6.46 

6.46 

0.72 

1 

1 

4 

4 

5.13 

5.26 

5.26 

0.77 

1 

1 

5 

5 

6.08 

4.44 

4.44 

0.82 

1 

6 

6 

7.03 

3.84 

3.84 

0.85 

1 

7 

7 

7.98 

3.38 

3.38 

0.87 

1 

8 

8 

8.93 

3.02 

3.02 

0.89 

1 

9 

9 

9.88 

2.73 

2.73 

0.91 

1 

10 

10 

10.83 

2.49 

2.49 

0.92 

NOTE — Variation  in  the  fineness  of  the  sand  and  in  the  consistency  of  the  mortar  may 
affect  the  yield  of  mortar  by  10%  in  either  direction. 

The  volume  of  mortar  refers  to  its  volume  in  a  plastic  condition  as  mixed,  not  to  its 
volume  after  ramming  or  hardening. 


89 


QUANTITIES    OF   MATERIAL  FOR  ONE   CUBIC   YARD    OF    RAMMED    CON- 
CRETE SHOWING  ALSO  THE  AMOUNT  OF  HYDRATED  LIME  ADDED 

TABLE  No.  5 


Proportions 

by 

Parts 

Proportions 

by 

Volume 

Quantities 
for 
One  Cubic  Yard 

Pounds  of  Hydrated  Lime 
Added  for 
One  Yard  Mixture 

Cement 

Sand 

Stone 

Cement 
Bbls. 

Sand 
Cu.  ft. 

Stone 
Cu.  ft. 

Cement 
Bbls. 

Sand 
Cu.  yd 

Stone 
Cu.  yd 

5% 
Ibs. 

10% 

Ibs. 

15% 
Ibs. 

20% 
Ibs. 

25% 
Ibs. 

1 
1 
1 

2 

2H 
3 

1 
1 
1 

3.8 
3.8 
3.8 

7.6 
9.5 
11.4 

2.73 
2.45 
2.20 

0.38 
0.34 
0.31 

0.77 
0.86 
0.94 

51 
46 
41 

103 
92 
83 

154 
138 
124 

206 
184 
165 

257 
230 
206 

VA 

ll/2 

iy2 

2 

&A 
3 

1 
1 
1 

5.7 
5.7 
5.7 

7.6 
9.5 
11.4 

2.40 
2.18 
2.00 

0.51 
0.46 
0.42 

0.68 
0.77 
0.84 

45 
41 
37 

90 
82 
75 

135 
123 
113 

180 
164 
150 

225 
205 
188 

2 
2 
2 
2 

3 

3^ 
4 

4^ 

1 
1 
1 
1 

7.6 
7.6 
7.6 
7.6 

11.4 
13.3 
15.2 
17.1 

1.81 
1.68 
1.57 
1.48 

0.51 
0.47 
0.44 
0.42 

0.76 
0.83 
0.88 
0.94 

34 
31 

29 

28 

68 
63 
59 
56 

102 
94 
88 

84 

136 
125 
117 
112 

170 
156 
146 
140 

&A 
&A 
&A 
&A 
&A 

&A 

VA 

3 

3>i 
4 
4^ 
5 
5^2 
6 

1 
1 
1 
1 
1 
1 
1 

9.5 
9.5 
9.5 
9.5 
9.5 
9.5 
9.5 

11.4 
13.3 
15.2 
17.1 
19.0 
20.9 
22.8 

1.66 
1.55 
.46 
.37 
.30 
.23 
.17 

0.58 
0.55 
0.51 
0.48 
0.46 
0.43 
0.41 

0.70 
0.76 
0.82 
0.87 
0.92 
0.95 
0.99 

31 

29 

27 
26 
24 
23 

22 

62 
58 
55 
52 
49 
46 
44 

93 

87 
82 
78 
73 
69 
66 

124 
116 
110 
104 
96 
92 
88 

155 
145 
137 
130 
123 
115 
110 

127 
120 
115 
110 
105 
100 
95 
90 
87 

1 
1 
1 

1 
1 
1 
1 
1 
1 

3 
3 
3 
3 
3 
3 
3 
3 
3 

4 

4^ 
5 
5^ 
6 
6^ 
7 
7^ 
8 

11.4 
11.4 
11.4 
11.4 
11.4 
11.4 
11.4 
11.4 
11.4 

15.2 
17.1 
19.0 
20.9 

22.8 
24.7 
26.6 
28.5 
30.4 

.36 
.28 
.22 
.16 
.11 
.06 
.01 
0.97 
0.93 

0.57 
0.54 
0.52 
0.49 
0.47 
0.45 
0.43 
0.41 
0.39 

0.77 
0.81 
0.86 
0.90 
0.94 
0.97 
0.99 
1.02 
1.05 

25 

24 
23 
22 
21 
20 
19 
18 
17 

51 

48 
46 
44 
42 
40 
38 
36 
35 

76 

72 
69 
66 
63 
60 
57 
54 
52 

102 
96 
92 

88 
84 
80 
76 
72 
70 

1 

1 
1 
1 
1 
1 

4 
4 
4 
4 
4 
4 

5 

6 
7 
8 
9 
10 

15.2 
15.2 
15.2 
15.2 
15.2 
15.2 

19.0 
22.8 
26.6 
30.4 
34.2 
38.0 

1.08 
0.99 
0.92 
0.85 
0.80 
0.75 

0.61 
0.56 
0.52 
0.48 
0.45 
0.42 

0.76 
0.84 
0.91 
0.96 
1.01 
1.06 

20 
18 
17 
16 
15 
14 

40 
37 
34 
32 
30 
28 

60 
55 
51 

48 
45 

42 

80 
74 
68 
64 
60 
56 

100 
92 
85 
80 

75 
70 

1 

5 

10 

1 

19.0 

38.0 

0.69 

0.49 

0.97 

13 

26 

39 

52 

65 

NOTES — The  above  table  for  quantities  of  cement  has  been  taken  from  Taylor  &  Thomp- 
son's "Concrete,  Plain  and  Reinforced."  The  quantities  of  hydrated  lime  have  been  cal- 
culated by  the  author. 

In  many  instances  the  amounts  are  even  fractions  of  a  sack  of  hydrate  (100  Ibs.),  i.  e., 
10%  in  a  1-2-4  is  practically  half  a  sack. 

In  case  where  the  amount  of  hydrate  called  for  is  not  a  convenient  part  of  a  sack,  it  is 
advisable  to  have  a  box  made  which  will  hold  the  required  amount.  This  is  easily  done,  as 
a  cubic  foot  of  hydrate  weighs  40  Ibs.  A  one  sack  mixture  would  require  the  addition  of  % 
the  amount  of  materials  and  a  2  sack  mixture  of  ^  the  amount. 


90 


INDEX 

SUBJECT  Page 


Aluminum 12—13 

Arenaceous  Limestone 21 

Argillaceous  Limestone 21 

Atom 11 

Atomic  Weights 12 

B 

Barrel 81 

Basic  Carbonate , 38 

Brigham,  S.  Y 42 

Brewer,    Bertram 74 

Bucket  Size 83 

Burning,  Chemical  change 14 

Bushel 81 

C 

Calcium 12-13 

Carbon 12-13 

Carbonates 13 

Cement — Hydrated  Lime  Mortar  Quantities 89 

Chalk 21 

Chapman,  Cloyd  M 35  to  37 

Chemistry  of  Lime 11  to  20 

Chemical  Symbols 12 

Classification 21 

Coal 31 

Composition — Calculation 18-19 

Compound 11 

Concrete  Cracking 66 

Concrete — Quantities  of  Materials 90 

Concrete  Water  Proofing 70  to  77 

Conglomerate  Limestone 21 

D 

Dolomite  Limestone 21 

91 


SUBJECT  page 
E 

Edfou 10 

Egypt 9 

Eldred  Process 31 

Element 1 1 

Emley,  Warren  E 37-56 

Etruscans ;  ;  .  .  10 

F 

Fue1 .....;......  30 

G 

Greeks 10 

H 

Hardening — Chemical  Change 16 

High  Calcium  Limestone 21 

Historical 9-10 

Hydrate — Calculating  Composition 19 

Hydrated  Lime 22 

Hydrated  Lime — Advantage  of 49  to  53-79-80 

Hydrated  Lime — Cement  Mortar — Quantities 87 

Hydrated  Lime — Chemical  Composition 46 

Hydrated  Lime — Definition 41-81 

Hydrated  Lime — Manufacture  of 41  to  45 

Hydrated  Lime  Mortar — Quantities .  87 

Hydrate  Paste . 82 

Hydrated  Lime — Properties  of 46  to  48 

Hydrated  Lime — Physical  Properties 47-48 

Hydrated  Lime — Specific  Gravity 47 

Hydrated  Lime  Specification 84 

Hydrated  Lime — Use  in  Concrete 63  to  77 

Hydrated  Lime— Use  of 49-50 

Hydrated  Lime — Weight 47-81 

Hydrates 13 

Hydrating — Chemical  Change 15 

Hydrating — Dodge  Process 42 

Hydrating — Modern  Methods  of 42 

Hydrating — Clyde  Process 42-43 

Hydrating — Kritzer  Process 43-44 

Hydrating — Pierce  Process 42 

Hydrating — Reaney  Process 43 

Hydrating — Lauman  Process 45 

Hydraulic  Lime 22 

Hydrogen 12-13 

Hydroxides 13 

92 


SUBJECT  Page 

I 

Iron 12-13 

J 

Jackson,  Chas.  T 25  to  27 

K 

Kiln— Aalborg 30 

Kiln— Continuous 24-26 

Kiln— Draw 26-27 

Kiln— Field 25-26 

Kiln— Intermittent 24 

Kiln— Pot 24-25-26 

Kiln— Producer  Gas .  31  to  32 

Kiln— Ring 26 

Kiln— Rotary 26-30 

Kiln— Schofer 30 

Kiln— Steel  Encased 28  to  30 

Kilns— Types 24 

Kiln— Vertical 26-28  to  30 

L 

Lazell,  E.  W 56-72-73 

Lime — Calcium 22 

Lime — Chemistry 11  to  20 

Lime — Classification  of 21  to  23 

Limestone — Classes  of 21 

"Lime  Cycle" 16-17 

Lime — Definition 22-84 

Lime — Fat 23 

Lime — Ground 22 

Lime — High  Calcium 22 

Lime — High  Magnesium 22 

Lime — Hydrated 22 

Lime — Hydraulic 23 

Lime — Hydraulic — Definition 22 

Lime — Lean 23 

Lime — Magnesium 22 

Lime — Manufacture  of 24  to  33 

Lime — Overburned 38 

Lime — Paste 81 

Lime — Paste — Aging 38 

Lime — Paste — Volume 81 

Lime — Paste — Water  in 36-37 

93 


SUBJECT  page 

Lime — Pulverized 22 

Lime — Run  of  Kiln 22 

Lime — Selected  Lump 22 

Lime — Slaking 34  to  40 

Lime — Types 22 

Lime — Weight 81 

Limestone — Composition 21 

Limestone — -Definition 21 

Limestone — Origin 21 

M 

Magnesium 12-13 

Magnesium — Limestone 21 

Marble 21 

Marl 21 

Mass 11 

Miller 9 

Molecular  Weight 12 

Molecule 11 

Mortars 49  to  62 

Mortar — Brick  or  Tile 54-55 

Mortar — Cement  Lime 56  to  62 

Mortar — Definition 83 

Mortar — Hydrated  Lime — Quantities 87 

Mortar— Metal  Lath 54 

Mortar  Mixing  Machine 52 

Mortars — Specifications 53-54-55 

Mortar — Strength  of 56  to  60 

Mortar— Tests  of 57  to  60-72  to  75 

Mortar— Wood  Lath 53-54 

Mortar — Weight 83 

0 

Ombos 10 

Oolite 21 

Oxides 13 

Oxygen 12-13 

Oxy-hydrate 38 

P 

Palladius 10 

Permeability  Tests 72  to  75 

Plasterers  Co 10 

Plastic — Definition 63 

Plasticity — Concrete 63-66 

Pliny 10 

Portland  Cement— Barrel 82 

94 


SUBJECT  Page 

Portland  Cement— Definition 82 

Portland  Cement  Paste 82 

Portland  Cement— Weight 82 

Producer  Gas 31 

Pyramids 9 

Pyramids — Cheops 10 

R 

Romans ^ ..................  10 

8 

Sack— Hydrate , 82 

Sand— Quality 

Sand — Specific  Gravity 82 

Sand — Specifications  for 52 

Sand— Weight 82 

Sand— Voids 82 

Shovels — Size 83 

Silicon 12-13 

Slaking— "Burned"  in 34-37-81 

Slaking— Chemical  Change 15-34-81 

Slaking — Chemical  Changes 34 

Slaking— Drowned 35-81 

Slaking — Dry  Methods 41 

Slaking— Italian  Method 39 

Slaking— Methods  of 34 

Slaking — Roman  Method 38 

Slaking— Water  Required 35-36-37-81 

Specification — Cement  Hydrate  Mortar 62 

Stucco 10 

Sulphur 12-13 

T 

Thomaston,  Me 25-26 

Thompson,  Sanford  E 74-75 


r 

Vicat 9 

Vitruvius 10-38 

W 

Wheelbarrows — Size 83 

Woolson,  Ira  H 56 

Wright,  W.  H 23 

95 


off 


N0\ 


MAR 


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